11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/pagemap.h> 230eeca283SRobert Love #include <linux/fsnotify.h> 241da177e4SLinus Torvalds #include <linux/personality.h> 251da177e4SLinus Torvalds #include <linux/security.h> 266146f0d5SMimi Zohar #include <linux/ima.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 345ad4e53bSAl Viro #include <linux/fs_struct.h> 351da177e4SLinus Torvalds #include <asm/uaccess.h> 361da177e4SLinus Torvalds 37e81e3f4dSEric Paris #include "internal.h" 38e81e3f4dSEric Paris 391da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 401da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 411da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 421da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 431da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 461da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 471da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 481da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 491da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 501da177e4SLinus Torvalds * the special cases of the former code. 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 531da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 541da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 571da177e4SLinus Torvalds * resolution to correspond with current state of the code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 601da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 611da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 621da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 631da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 641da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 651da177e4SLinus Torvalds */ 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 681da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 691da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 701da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 711da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 721da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7325985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1111da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1121da177e4SLinus Torvalds * kernel data space before using them.. 1131da177e4SLinus Torvalds * 1141da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1151da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1161da177e4SLinus Torvalds */ 117858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1181da177e4SLinus Torvalds { 1191da177e4SLinus Torvalds int retval; 1201da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1231da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1241da177e4SLinus Torvalds return -EFAULT; 1251da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1261da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1301da177e4SLinus Torvalds if (retval > 0) { 1311da177e4SLinus Torvalds if (retval < len) 1321da177e4SLinus Torvalds return 0; 1331da177e4SLinus Torvalds return -ENAMETOOLONG; 1341da177e4SLinus Torvalds } else if (!retval) 1351da177e4SLinus Torvalds retval = -ENOENT; 1361da177e4SLinus Torvalds return retval; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 139f52e0c11SAl Viro static char *getname_flags(const char __user * filename, int flags) 1401da177e4SLinus Torvalds { 1411da177e4SLinus Torvalds char *tmp, *result; 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1441da177e4SLinus Torvalds tmp = __getname(); 1451da177e4SLinus Torvalds if (tmp) { 1461da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds result = tmp; 1491da177e4SLinus Torvalds if (retval < 0) { 150f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 155f52e0c11SAl Viro } 1561da177e4SLinus Torvalds audit_getname(result); 1571da177e4SLinus Torvalds return result; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 160f52e0c11SAl Viro char *getname(const char __user * filename) 161f52e0c11SAl Viro { 162f52e0c11SAl Viro return getname_flags(filename, 0); 163f52e0c11SAl Viro } 164f52e0c11SAl Viro 1651da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1661da177e4SLinus Torvalds void putname(const char *name) 1671da177e4SLinus Torvalds { 1685ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1691da177e4SLinus Torvalds audit_putname(name); 1701da177e4SLinus Torvalds else 1711da177e4SLinus Torvalds __putname(name); 1721da177e4SLinus Torvalds } 1731da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1741da177e4SLinus Torvalds #endif 1751da177e4SLinus Torvalds 1765909ccaaSLinus Torvalds /* 1775909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1785909ccaaSLinus Torvalds */ 1797e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 1805909ccaaSLinus Torvalds { 1817e40145eSAl Viro int (*check_acl)(struct inode *inode, int mask); 18226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 1835909ccaaSLinus Torvalds 1849c2c7039SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK; 1855909ccaaSLinus Torvalds 186e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 187e795b717SSerge E. Hallyn goto other_perms; 188e795b717SSerge E. Hallyn 1895909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1905909ccaaSLinus Torvalds mode >>= 6; 1915909ccaaSLinus Torvalds else { 192178ea735SAl Viro check_acl = inode->i_op->check_acl; 1935909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1947e40145eSAl Viro int error = check_acl(inode, mask); 1955909ccaaSLinus Torvalds if (error != -EAGAIN) 1965909ccaaSLinus Torvalds return error; 1975909ccaaSLinus Torvalds } 1985909ccaaSLinus Torvalds 1995909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2005909ccaaSLinus Torvalds mode >>= 3; 2015909ccaaSLinus Torvalds } 2025909ccaaSLinus Torvalds 203e795b717SSerge E. Hallyn other_perms: 2045909ccaaSLinus Torvalds /* 2055909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2065909ccaaSLinus Torvalds */ 2079c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2085909ccaaSLinus Torvalds return 0; 2095909ccaaSLinus Torvalds return -EACCES; 2105909ccaaSLinus Torvalds } 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds /** 2131da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2141da177e4SLinus Torvalds * @inode: inode to check access rights for 2151da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 21639191628SRandy Dunlap * @flags: IPERM_FLAG_ flags. 2171da177e4SLinus Torvalds * 2181da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2191da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2201da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 221b74c79e9SNick Piggin * are used for other things. 222b74c79e9SNick Piggin * 223b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 224b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 225b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2261da177e4SLinus Torvalds */ 2272830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2281da177e4SLinus Torvalds { 2295909ccaaSLinus Torvalds int ret; 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds /* 2325909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2331da177e4SLinus Torvalds */ 2347e40145eSAl Viro ret = acl_permission_check(inode, mask); 2355909ccaaSLinus Torvalds if (ret != -EACCES) 2365909ccaaSLinus Torvalds return ret; 2371da177e4SLinus Torvalds 238d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 239d594e7ecSAl Viro /* DACs are overridable for directories */ 240d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 241d594e7ecSAl Viro return 0; 242d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 243d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 244d594e7ecSAl Viro return 0; 245d594e7ecSAl Viro return -EACCES; 246d594e7ecSAl Viro } 2471da177e4SLinus Torvalds /* 2481da177e4SLinus Torvalds * Read/write DACs are always overridable. 249d594e7ecSAl Viro * Executable DACs are overridable when there is 250d594e7ecSAl Viro * at least one exec bit set. 2511da177e4SLinus Torvalds */ 252d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 253e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 2541da177e4SLinus Torvalds return 0; 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds /* 2571da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2581da177e4SLinus Torvalds */ 2597ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 260d594e7ecSAl Viro if (mask == MAY_READ) 261e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 2621da177e4SLinus Torvalds return 0; 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds return -EACCES; 2651da177e4SLinus Torvalds } 2661da177e4SLinus Torvalds 267cb23beb5SChristoph Hellwig /** 268cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 269cb23beb5SChristoph Hellwig * @inode: inode to check permission on 270cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 271cb23beb5SChristoph Hellwig * 272cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 273cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 274cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 275cb23beb5SChristoph Hellwig * are used for other things. 276cb23beb5SChristoph Hellwig */ 277f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2781da177e4SLinus Torvalds { 279e6305c43SAl Viro int retval; 2801da177e4SLinus Torvalds 2811da177e4SLinus Torvalds if (mask & MAY_WRITE) { 28222590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2831da177e4SLinus Torvalds 2841da177e4SLinus Torvalds /* 2851da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2861da177e4SLinus Torvalds */ 2871da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2881da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2891da177e4SLinus Torvalds return -EROFS; 2901da177e4SLinus Torvalds 2911da177e4SLinus Torvalds /* 2921da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2931da177e4SLinus Torvalds */ 2941da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2951da177e4SLinus Torvalds return -EACCES; 2961da177e4SLinus Torvalds } 2971da177e4SLinus Torvalds 298acfa4380SAl Viro if (inode->i_op->permission) 29910556cb2SAl Viro retval = inode->i_op->permission(inode, mask); 300f696a365SMiklos Szeredi else 3012830ba7fSAl Viro retval = generic_permission(inode, mask); 302f696a365SMiklos Szeredi 3031da177e4SLinus Torvalds if (retval) 3041da177e4SLinus Torvalds return retval; 3051da177e4SLinus Torvalds 30608ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 30708ce5f16SSerge E. Hallyn if (retval) 30808ce5f16SSerge E. Hallyn return retval; 30908ce5f16SSerge E. Hallyn 310d09ca739SEric Paris return security_inode_permission(inode, mask); 3111da177e4SLinus Torvalds } 3121da177e4SLinus Torvalds 313f4d6ff89SAl Viro /** 3145dd784d0SJan Blunck * path_get - get a reference to a path 3155dd784d0SJan Blunck * @path: path to get the reference to 3165dd784d0SJan Blunck * 3175dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3185dd784d0SJan Blunck */ 3195dd784d0SJan Blunck void path_get(struct path *path) 3205dd784d0SJan Blunck { 3215dd784d0SJan Blunck mntget(path->mnt); 3225dd784d0SJan Blunck dget(path->dentry); 3235dd784d0SJan Blunck } 3245dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3255dd784d0SJan Blunck 3265dd784d0SJan Blunck /** 3271d957f9bSJan Blunck * path_put - put a reference to a path 3281d957f9bSJan Blunck * @path: path to put the reference to 3291d957f9bSJan Blunck * 3301d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3311d957f9bSJan Blunck */ 3321d957f9bSJan Blunck void path_put(struct path *path) 3331da177e4SLinus Torvalds { 3341d957f9bSJan Blunck dput(path->dentry); 3351d957f9bSJan Blunck mntput(path->mnt); 3361da177e4SLinus Torvalds } 3371d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3381da177e4SLinus Torvalds 33919660af7SAl Viro /* 34031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 34119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 34219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 34319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 34419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 34519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 34619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 34719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 34831e6b01fSNick Piggin */ 34931e6b01fSNick Piggin 35031e6b01fSNick Piggin /** 35119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 35219660af7SAl Viro * @nd: nameidata pathwalk data 35319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 35439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 35531e6b01fSNick Piggin * 35619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 35719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 35819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 35931e6b01fSNick Piggin */ 36019660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 36131e6b01fSNick Piggin { 36231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 36331e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 3645b6ca027SAl Viro int want_root = 0; 36531e6b01fSNick Piggin 36631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 3675b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 3685b6ca027SAl Viro want_root = 1; 36931e6b01fSNick Piggin spin_lock(&fs->lock); 37031e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 37131e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 37231e6b01fSNick Piggin goto err_root; 37331e6b01fSNick Piggin } 37431e6b01fSNick Piggin spin_lock(&parent->d_lock); 37519660af7SAl Viro if (!dentry) { 37619660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 37719660af7SAl Viro goto err_parent; 37819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 37919660af7SAl Viro } else { 38094c0d4ecSAl Viro if (dentry->d_parent != parent) 38194c0d4ecSAl Viro goto err_parent; 38231e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 38331e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 38419660af7SAl Viro goto err_child; 38531e6b01fSNick Piggin /* 38619660af7SAl Viro * If the sequence check on the child dentry passed, then 38719660af7SAl Viro * the child has not been removed from its parent. This 38819660af7SAl Viro * means the parent dentry must be valid and able to take 38919660af7SAl Viro * a reference at this point. 39031e6b01fSNick Piggin */ 39131e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 39231e6b01fSNick Piggin BUG_ON(!parent->d_count); 39331e6b01fSNick Piggin parent->d_count++; 39431e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 39519660af7SAl Viro } 39631e6b01fSNick Piggin spin_unlock(&parent->d_lock); 3975b6ca027SAl Viro if (want_root) { 39831e6b01fSNick Piggin path_get(&nd->root); 39931e6b01fSNick Piggin spin_unlock(&fs->lock); 40031e6b01fSNick Piggin } 40131e6b01fSNick Piggin mntget(nd->path.mnt); 40231e6b01fSNick Piggin 40331e6b01fSNick Piggin rcu_read_unlock(); 40431e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 40531e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 40631e6b01fSNick Piggin return 0; 40719660af7SAl Viro 40819660af7SAl Viro err_child: 40931e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 41019660af7SAl Viro err_parent: 41131e6b01fSNick Piggin spin_unlock(&parent->d_lock); 41231e6b01fSNick Piggin err_root: 4135b6ca027SAl Viro if (want_root) 41431e6b01fSNick Piggin spin_unlock(&fs->lock); 41531e6b01fSNick Piggin return -ECHILD; 41631e6b01fSNick Piggin } 41731e6b01fSNick Piggin 41831e6b01fSNick Piggin /** 419834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 420834f2a4aSTrond Myklebust * @nd: pointer to nameidata 421834f2a4aSTrond Myklebust */ 422834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 423834f2a4aSTrond Myklebust { 4242dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4252dab5974SLinus Torvalds 4262dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4272dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4282dab5974SLinus Torvalds put_filp(file); 429834f2a4aSTrond Myklebust else 4302dab5974SLinus Torvalds fput(file); 4312dab5974SLinus Torvalds } 432834f2a4aSTrond Myklebust } 433834f2a4aSTrond Myklebust 434f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 43534286d66SNick Piggin { 436f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 43734286d66SNick Piggin } 43834286d66SNick Piggin 439f5e1c1c1SAl Viro static struct dentry * 440bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 441bcdc5e01SIan Kent { 442f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 443bcdc5e01SIan Kent if (unlikely(status <= 0)) { 444bcdc5e01SIan Kent /* 445bcdc5e01SIan Kent * The dentry failed validation. 446bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 447bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 448bcdc5e01SIan Kent * to return a fail status. 449bcdc5e01SIan Kent */ 45034286d66SNick Piggin if (status < 0) { 45134286d66SNick Piggin dput(dentry); 45234286d66SNick Piggin dentry = ERR_PTR(status); 453f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 454bcdc5e01SIan Kent dput(dentry); 455bcdc5e01SIan Kent dentry = NULL; 456bcdc5e01SIan Kent } 457bcdc5e01SIan Kent } 458f5e1c1c1SAl Viro return dentry; 459f5e1c1c1SAl Viro } 460f5e1c1c1SAl Viro 4619f1fafeeSAl Viro /** 4629f1fafeeSAl Viro * complete_walk - successful completion of path walk 4639f1fafeeSAl Viro * @nd: pointer nameidata 46439159de2SJeff Layton * 4659f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 4669f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 4679f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 4689f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 4699f1fafeeSAl Viro * need to drop nd->path. 47039159de2SJeff Layton */ 4719f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 47239159de2SJeff Layton { 47316c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 47439159de2SJeff Layton int status; 47539159de2SJeff Layton 4769f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 4779f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 4789f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 4799f1fafeeSAl Viro nd->root.mnt = NULL; 4809f1fafeeSAl Viro spin_lock(&dentry->d_lock); 4819f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 4829f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 4839f1fafeeSAl Viro rcu_read_unlock(); 4849f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 4859f1fafeeSAl Viro return -ECHILD; 4869f1fafeeSAl Viro } 4879f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 4889f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 4899f1fafeeSAl Viro mntget(nd->path.mnt); 4909f1fafeeSAl Viro rcu_read_unlock(); 4919f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 4929f1fafeeSAl Viro } 4939f1fafeeSAl Viro 49416c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 49539159de2SJeff Layton return 0; 49639159de2SJeff Layton 49716c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 49816c2cd71SAl Viro return 0; 49916c2cd71SAl Viro 50016c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 50116c2cd71SAl Viro return 0; 50216c2cd71SAl Viro 50316c2cd71SAl Viro /* Note: we do not d_invalidate() */ 50434286d66SNick Piggin status = d_revalidate(dentry, nd); 50539159de2SJeff Layton if (status > 0) 50639159de2SJeff Layton return 0; 50739159de2SJeff Layton 50816c2cd71SAl Viro if (!status) 50939159de2SJeff Layton status = -ESTALE; 51016c2cd71SAl Viro 5119f1fafeeSAl Viro path_put(&nd->path); 51239159de2SJeff Layton return status; 51339159de2SJeff Layton } 51439159de2SJeff Layton 5152a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5162a737871SAl Viro { 517f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 518f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5192a737871SAl Viro } 5202a737871SAl Viro 5216de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5226de88d72SAl Viro 52331e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 52431e6b01fSNick Piggin { 52531e6b01fSNick Piggin if (!nd->root.mnt) { 52631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 527c28cc364SNick Piggin unsigned seq; 528c28cc364SNick Piggin 529c28cc364SNick Piggin do { 530c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 53131e6b01fSNick Piggin nd->root = fs->root; 532c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 533c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 53431e6b01fSNick Piggin } 53531e6b01fSNick Piggin } 53631e6b01fSNick Piggin 537f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5381da177e4SLinus Torvalds { 53931e6b01fSNick Piggin int ret; 54031e6b01fSNick Piggin 5411da177e4SLinus Torvalds if (IS_ERR(link)) 5421da177e4SLinus Torvalds goto fail; 5431da177e4SLinus Torvalds 5441da177e4SLinus Torvalds if (*link == '/') { 5452a737871SAl Viro set_root(nd); 5461d957f9bSJan Blunck path_put(&nd->path); 5472a737871SAl Viro nd->path = nd->root; 5482a737871SAl Viro path_get(&nd->root); 54916c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 5501da177e4SLinus Torvalds } 55131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 552b4091d5fSChristoph Hellwig 55331e6b01fSNick Piggin ret = link_path_walk(link, nd); 55431e6b01fSNick Piggin return ret; 5551da177e4SLinus Torvalds fail: 5561d957f9bSJan Blunck path_put(&nd->path); 5571da177e4SLinus Torvalds return PTR_ERR(link); 5581da177e4SLinus Torvalds } 5591da177e4SLinus Torvalds 5601d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 561051d3812SIan Kent { 562051d3812SIan Kent dput(path->dentry); 5634ac91378SJan Blunck if (path->mnt != nd->path.mnt) 564051d3812SIan Kent mntput(path->mnt); 565051d3812SIan Kent } 566051d3812SIan Kent 5677b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 5687b9337aaSNick Piggin struct nameidata *nd) 569051d3812SIan Kent { 57031e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 5714ac91378SJan Blunck dput(nd->path.dentry); 57231e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 5734ac91378SJan Blunck mntput(nd->path.mnt); 5749a229683SHuang Shijie } 57531e6b01fSNick Piggin nd->path.mnt = path->mnt; 5764ac91378SJan Blunck nd->path.dentry = path->dentry; 577051d3812SIan Kent } 578051d3812SIan Kent 579574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 580574197e0SAl Viro { 581574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 582574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 583574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 584574197e0SAl Viro path_put(link); 585574197e0SAl Viro } 586574197e0SAl Viro 587def4af30SAl Viro static __always_inline int 588574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 5891da177e4SLinus Torvalds { 5901da177e4SLinus Torvalds int error; 5917b9337aaSNick Piggin struct dentry *dentry = link->dentry; 5921da177e4SLinus Torvalds 593844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 594844a3917SAl Viro 5950e794589SAl Viro if (link->mnt == nd->path.mnt) 5960e794589SAl Viro mntget(link->mnt); 5970e794589SAl Viro 598574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 599574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 600574197e0SAl Viro path_put(&nd->path); 601574197e0SAl Viro return -ELOOP; 602574197e0SAl Viro } 603574197e0SAl Viro cond_resched(); 604574197e0SAl Viro current->total_link_count++; 605574197e0SAl Viro 6067b9337aaSNick Piggin touch_atime(link->mnt, dentry); 6071da177e4SLinus Torvalds nd_set_link(nd, NULL); 608cd4e91d3SAl Viro 60936f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 61036f3b4f6SAl Viro if (error) { 61136f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 61236f3b4f6SAl Viro path_put(&nd->path); 61336f3b4f6SAl Viro return error; 61436f3b4f6SAl Viro } 61536f3b4f6SAl Viro 61686acdca1SAl Viro nd->last_type = LAST_BIND; 617def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 618def4af30SAl Viro error = PTR_ERR(*p); 619def4af30SAl Viro if (!IS_ERR(*p)) { 6201da177e4SLinus Torvalds char *s = nd_get_link(nd); 621cc314eefSLinus Torvalds error = 0; 6221da177e4SLinus Torvalds if (s) 6231da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 624bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 62516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 626b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 627b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 628bcda7652SAl Viro /* stepped on a _really_ weird one */ 629bcda7652SAl Viro path_put(&nd->path); 630bcda7652SAl Viro error = -ELOOP; 631bcda7652SAl Viro } 632bcda7652SAl Viro } 6331da177e4SLinus Torvalds } 6341da177e4SLinus Torvalds return error; 6351da177e4SLinus Torvalds } 6361da177e4SLinus Torvalds 63731e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 63831e6b01fSNick Piggin { 63931e6b01fSNick Piggin struct vfsmount *parent; 64031e6b01fSNick Piggin struct dentry *mountpoint; 64131e6b01fSNick Piggin 64231e6b01fSNick Piggin parent = path->mnt->mnt_parent; 64331e6b01fSNick Piggin if (parent == path->mnt) 64431e6b01fSNick Piggin return 0; 64531e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 64631e6b01fSNick Piggin path->dentry = mountpoint; 64731e6b01fSNick Piggin path->mnt = parent; 64831e6b01fSNick Piggin return 1; 64931e6b01fSNick Piggin } 65031e6b01fSNick Piggin 651bab77ebfSAl Viro int follow_up(struct path *path) 6521da177e4SLinus Torvalds { 6531da177e4SLinus Torvalds struct vfsmount *parent; 6541da177e4SLinus Torvalds struct dentry *mountpoint; 65599b7db7bSNick Piggin 65699b7db7bSNick Piggin br_read_lock(vfsmount_lock); 657bab77ebfSAl Viro parent = path->mnt->mnt_parent; 658bab77ebfSAl Viro if (parent == path->mnt) { 65999b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 6601da177e4SLinus Torvalds return 0; 6611da177e4SLinus Torvalds } 6621da177e4SLinus Torvalds mntget(parent); 663bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 66499b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 665bab77ebfSAl Viro dput(path->dentry); 666bab77ebfSAl Viro path->dentry = mountpoint; 667bab77ebfSAl Viro mntput(path->mnt); 668bab77ebfSAl Viro path->mnt = parent; 6691da177e4SLinus Torvalds return 1; 6701da177e4SLinus Torvalds } 6711da177e4SLinus Torvalds 672b5c84bf6SNick Piggin /* 6739875cf80SDavid Howells * Perform an automount 6749875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 6759875cf80SDavid Howells * were called with. 6761da177e4SLinus Torvalds */ 6779875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 6789875cf80SDavid Howells bool *need_mntput) 67931e6b01fSNick Piggin { 6809875cf80SDavid Howells struct vfsmount *mnt; 681ea5b778aSDavid Howells int err; 6829875cf80SDavid Howells 6839875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 6849875cf80SDavid Howells return -EREMOTE; 6859875cf80SDavid Howells 6866f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 6876f45b656SDavid Howells * and this is the terminal part of the path. 6886f45b656SDavid Howells */ 6896f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 6906f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 6916f45b656SDavid Howells 6929875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 6939875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 6949875cf80SDavid Howells * or wants to open the mounted directory. 6959875cf80SDavid Howells * 6969875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 6979875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 6989875cf80SDavid Howells * appended a '/' to the name. 6999875cf80SDavid Howells */ 7009875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 7019875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 7029875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 7039875cf80SDavid Howells return -EISDIR; 7049875cf80SDavid Howells 7059875cf80SDavid Howells current->total_link_count++; 7069875cf80SDavid Howells if (current->total_link_count >= 40) 7079875cf80SDavid Howells return -ELOOP; 7089875cf80SDavid Howells 7099875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7109875cf80SDavid Howells if (IS_ERR(mnt)) { 7119875cf80SDavid Howells /* 7129875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7139875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7149875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7159875cf80SDavid Howells * 7169875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7179875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7189875cf80SDavid Howells * the path is inaccessible and we should say so. 7199875cf80SDavid Howells */ 7209875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 7219875cf80SDavid Howells return -EREMOTE; 7229875cf80SDavid Howells return PTR_ERR(mnt); 72331e6b01fSNick Piggin } 724ea5b778aSDavid Howells 7259875cf80SDavid Howells if (!mnt) /* mount collision */ 7269875cf80SDavid Howells return 0; 7279875cf80SDavid Howells 7288aef1884SAl Viro if (!*need_mntput) { 7298aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7308aef1884SAl Viro mntget(path->mnt); 7318aef1884SAl Viro *need_mntput = true; 7328aef1884SAl Viro } 73319a167afSAl Viro err = finish_automount(mnt, path); 734ea5b778aSDavid Howells 735ea5b778aSDavid Howells switch (err) { 736ea5b778aSDavid Howells case -EBUSY: 737ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 73819a167afSAl Viro return 0; 739ea5b778aSDavid Howells case 0: 7408aef1884SAl Viro path_put(path); 7419875cf80SDavid Howells path->mnt = mnt; 7429875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7439875cf80SDavid Howells return 0; 74419a167afSAl Viro default: 74519a167afSAl Viro return err; 7469875cf80SDavid Howells } 74719a167afSAl Viro 748ea5b778aSDavid Howells } 7499875cf80SDavid Howells 7509875cf80SDavid Howells /* 7519875cf80SDavid Howells * Handle a dentry that is managed in some way. 752cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7539875cf80SDavid Howells * - Flagged as mountpoint 7549875cf80SDavid Howells * - Flagged as automount point 7559875cf80SDavid Howells * 7569875cf80SDavid Howells * This may only be called in refwalk mode. 7579875cf80SDavid Howells * 7589875cf80SDavid Howells * Serialization is taken care of in namespace.c 7599875cf80SDavid Howells */ 7609875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7619875cf80SDavid Howells { 7628aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 7639875cf80SDavid Howells unsigned managed; 7649875cf80SDavid Howells bool need_mntput = false; 7658aef1884SAl Viro int ret = 0; 7669875cf80SDavid Howells 7679875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 7689875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 7699875cf80SDavid Howells * the components of that value change under us */ 7709875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 7719875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 7729875cf80SDavid Howells unlikely(managed != 0)) { 773cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 774cc53ce53SDavid Howells * being held. */ 775cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 776cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 777cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 7781aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 779cc53ce53SDavid Howells if (ret < 0) 7808aef1884SAl Viro break; 781cc53ce53SDavid Howells } 782cc53ce53SDavid Howells 7839875cf80SDavid Howells /* Transit to a mounted filesystem. */ 7849875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 7859875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 7869875cf80SDavid Howells if (mounted) { 7879875cf80SDavid Howells dput(path->dentry); 7889875cf80SDavid Howells if (need_mntput) 789463ffb2eSAl Viro mntput(path->mnt); 790463ffb2eSAl Viro path->mnt = mounted; 791463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 7929875cf80SDavid Howells need_mntput = true; 7939875cf80SDavid Howells continue; 794463ffb2eSAl Viro } 795463ffb2eSAl Viro 7969875cf80SDavid Howells /* Something is mounted on this dentry in another 7979875cf80SDavid Howells * namespace and/or whatever was mounted there in this 7989875cf80SDavid Howells * namespace got unmounted before we managed to get the 7999875cf80SDavid Howells * vfsmount_lock */ 8001da177e4SLinus Torvalds } 8019875cf80SDavid Howells 8029875cf80SDavid Howells /* Handle an automount point */ 8039875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8049875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8059875cf80SDavid Howells if (ret < 0) 8068aef1884SAl Viro break; 8079875cf80SDavid Howells continue; 8089875cf80SDavid Howells } 8099875cf80SDavid Howells 8109875cf80SDavid Howells /* We didn't change the current path point */ 8119875cf80SDavid Howells break; 8129875cf80SDavid Howells } 8138aef1884SAl Viro 8148aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8158aef1884SAl Viro mntput(path->mnt); 8168aef1884SAl Viro if (ret == -EISDIR) 8178aef1884SAl Viro ret = 0; 8188aef1884SAl Viro return ret; 8191da177e4SLinus Torvalds } 8201da177e4SLinus Torvalds 821cc53ce53SDavid Howells int follow_down_one(struct path *path) 8221da177e4SLinus Torvalds { 8231da177e4SLinus Torvalds struct vfsmount *mounted; 8241da177e4SLinus Torvalds 8251c755af4SAl Viro mounted = lookup_mnt(path); 8261da177e4SLinus Torvalds if (mounted) { 8279393bd07SAl Viro dput(path->dentry); 8289393bd07SAl Viro mntput(path->mnt); 8299393bd07SAl Viro path->mnt = mounted; 8309393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8311da177e4SLinus Torvalds return 1; 8321da177e4SLinus Torvalds } 8331da177e4SLinus Torvalds return 0; 8341da177e4SLinus Torvalds } 8351da177e4SLinus Torvalds 83662a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 83762a7375eSIan Kent { 83862a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 83962a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 84062a7375eSIan Kent } 84162a7375eSIan Kent 8429875cf80SDavid Howells /* 843287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 844287548e4SAl Viro * we meet a managed dentry that would need blocking. 8459875cf80SDavid Howells */ 8469875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 847287548e4SAl Viro struct inode **inode) 8489875cf80SDavid Howells { 84962a7375eSIan Kent for (;;) { 8509875cf80SDavid Howells struct vfsmount *mounted; 85162a7375eSIan Kent /* 85262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 85362a7375eSIan Kent * that wants to block transit. 85462a7375eSIan Kent */ 855287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 856ab90911fSDavid Howells return false; 85762a7375eSIan Kent 85862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 85962a7375eSIan Kent break; 86062a7375eSIan Kent 8619875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 8629875cf80SDavid Howells if (!mounted) 8639875cf80SDavid Howells break; 8649875cf80SDavid Howells path->mnt = mounted; 8659875cf80SDavid Howells path->dentry = mounted->mnt_root; 8669875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 86759430262SLinus Torvalds /* 86859430262SLinus Torvalds * Update the inode too. We don't need to re-check the 86959430262SLinus Torvalds * dentry sequence number here after this d_inode read, 87059430262SLinus Torvalds * because a mount-point is always pinned. 87159430262SLinus Torvalds */ 87259430262SLinus Torvalds *inode = path->dentry->d_inode; 8739875cf80SDavid Howells } 8749875cf80SDavid Howells return true; 8759875cf80SDavid Howells } 8769875cf80SDavid Howells 877dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 878287548e4SAl Viro { 879dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 880287548e4SAl Viro struct vfsmount *mounted; 881dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 882287548e4SAl Viro if (!mounted) 883287548e4SAl Viro break; 884dea39376SAl Viro nd->path.mnt = mounted; 885dea39376SAl Viro nd->path.dentry = mounted->mnt_root; 886dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 887287548e4SAl Viro } 888287548e4SAl Viro } 889287548e4SAl Viro 89031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 89131e6b01fSNick Piggin { 89231e6b01fSNick Piggin set_root_rcu(nd); 89331e6b01fSNick Piggin 89431e6b01fSNick Piggin while (1) { 89531e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 89631e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 89731e6b01fSNick Piggin break; 89831e6b01fSNick Piggin } 89931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 90031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 90131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 90231e6b01fSNick Piggin unsigned seq; 90331e6b01fSNick Piggin 90431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 90531e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 906ef7562d5SAl Viro goto failed; 90731e6b01fSNick Piggin nd->path.dentry = parent; 90831e6b01fSNick Piggin nd->seq = seq; 90931e6b01fSNick Piggin break; 91031e6b01fSNick Piggin } 91131e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 91231e6b01fSNick Piggin break; 91331e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 91431e6b01fSNick Piggin } 915dea39376SAl Viro follow_mount_rcu(nd); 916dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 91731e6b01fSNick Piggin return 0; 918ef7562d5SAl Viro 919ef7562d5SAl Viro failed: 920ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9215b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 922ef7562d5SAl Viro nd->root.mnt = NULL; 923ef7562d5SAl Viro rcu_read_unlock(); 924ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 925ef7562d5SAl Viro return -ECHILD; 92631e6b01fSNick Piggin } 92731e6b01fSNick Piggin 9289875cf80SDavid Howells /* 929cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 930cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 931cc53ce53SDavid Howells * caller is permitted to proceed or not. 932cc53ce53SDavid Howells */ 9337cc90cc3SAl Viro int follow_down(struct path *path) 934cc53ce53SDavid Howells { 935cc53ce53SDavid Howells unsigned managed; 936cc53ce53SDavid Howells int ret; 937cc53ce53SDavid Howells 938cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 939cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 940cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 941cc53ce53SDavid Howells * being held. 942cc53ce53SDavid Howells * 943cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 944cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 945cc53ce53SDavid Howells * other than its daemon the right to mount on its 946cc53ce53SDavid Howells * superstructure. 947cc53ce53SDavid Howells * 948cc53ce53SDavid Howells * The filesystem may sleep at this point. 949cc53ce53SDavid Howells */ 950cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 951cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 952cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 953ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 9541aed3e42SAl Viro path->dentry, false); 955cc53ce53SDavid Howells if (ret < 0) 956cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 957cc53ce53SDavid Howells } 958cc53ce53SDavid Howells 959cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 960cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 961cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 962cc53ce53SDavid Howells if (!mounted) 963cc53ce53SDavid Howells break; 964cc53ce53SDavid Howells dput(path->dentry); 965cc53ce53SDavid Howells mntput(path->mnt); 966cc53ce53SDavid Howells path->mnt = mounted; 967cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 968cc53ce53SDavid Howells continue; 969cc53ce53SDavid Howells } 970cc53ce53SDavid Howells 971cc53ce53SDavid Howells /* Don't handle automount points here */ 972cc53ce53SDavid Howells break; 973cc53ce53SDavid Howells } 974cc53ce53SDavid Howells return 0; 975cc53ce53SDavid Howells } 976cc53ce53SDavid Howells 977cc53ce53SDavid Howells /* 9789875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 9799875cf80SDavid Howells */ 9809875cf80SDavid Howells static void follow_mount(struct path *path) 9819875cf80SDavid Howells { 9829875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 9839875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9849875cf80SDavid Howells if (!mounted) 9859875cf80SDavid Howells break; 9869875cf80SDavid Howells dput(path->dentry); 9879875cf80SDavid Howells mntput(path->mnt); 9889875cf80SDavid Howells path->mnt = mounted; 9899875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 9909875cf80SDavid Howells } 9919875cf80SDavid Howells } 9929875cf80SDavid Howells 99331e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 9941da177e4SLinus Torvalds { 9952a737871SAl Viro set_root(nd); 996e518ddb7SAndreas Mohr 9971da177e4SLinus Torvalds while(1) { 9984ac91378SJan Blunck struct dentry *old = nd->path.dentry; 9991da177e4SLinus Torvalds 10002a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10012a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10021da177e4SLinus Torvalds break; 10031da177e4SLinus Torvalds } 10044ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10053088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10063088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10071da177e4SLinus Torvalds dput(old); 10081da177e4SLinus Torvalds break; 10091da177e4SLinus Torvalds } 10103088dd70SAl Viro if (!follow_up(&nd->path)) 10111da177e4SLinus Torvalds break; 10121da177e4SLinus Torvalds } 101379ed0226SAl Viro follow_mount(&nd->path); 101431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10151da177e4SLinus Torvalds } 10161da177e4SLinus Torvalds 10171da177e4SLinus Torvalds /* 1018baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1019baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1020baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1021baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1022baa03890SNick Piggin */ 1023baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1024baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1025baa03890SNick Piggin { 1026baa03890SNick Piggin struct inode *inode = parent->d_inode; 1027baa03890SNick Piggin struct dentry *dentry; 1028baa03890SNick Piggin struct dentry *old; 1029baa03890SNick Piggin 1030baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1031baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1032baa03890SNick Piggin return ERR_PTR(-ENOENT); 1033baa03890SNick Piggin 1034baa03890SNick Piggin dentry = d_alloc(parent, name); 1035baa03890SNick Piggin if (unlikely(!dentry)) 1036baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1037baa03890SNick Piggin 1038baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1039baa03890SNick Piggin if (unlikely(old)) { 1040baa03890SNick Piggin dput(dentry); 1041baa03890SNick Piggin dentry = old; 1042baa03890SNick Piggin } 1043baa03890SNick Piggin return dentry; 1044baa03890SNick Piggin } 1045baa03890SNick Piggin 1046baa03890SNick Piggin /* 104744396f4bSJosef Bacik * We already have a dentry, but require a lookup to be performed on the parent 104844396f4bSJosef Bacik * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. 104944396f4bSJosef Bacik * parent->d_inode->i_mutex must be held. d_lookup must have verified that no 105044396f4bSJosef Bacik * child exists while under i_mutex. 105144396f4bSJosef Bacik */ 105244396f4bSJosef Bacik static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, 105344396f4bSJosef Bacik struct nameidata *nd) 105444396f4bSJosef Bacik { 105544396f4bSJosef Bacik struct inode *inode = parent->d_inode; 105644396f4bSJosef Bacik struct dentry *old; 105744396f4bSJosef Bacik 105844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 105944396f4bSJosef Bacik if (unlikely(IS_DEADDIR(inode))) 106044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 106144396f4bSJosef Bacik 106244396f4bSJosef Bacik old = inode->i_op->lookup(inode, dentry, nd); 106344396f4bSJosef Bacik if (unlikely(old)) { 106444396f4bSJosef Bacik dput(dentry); 106544396f4bSJosef Bacik dentry = old; 106644396f4bSJosef Bacik } 106744396f4bSJosef Bacik return dentry; 106844396f4bSJosef Bacik } 106944396f4bSJosef Bacik 107044396f4bSJosef Bacik /* 10711da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 10721da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 10731da177e4SLinus Torvalds * It _is_ time-critical. 10741da177e4SLinus Torvalds */ 10751da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 107631e6b01fSNick Piggin struct path *path, struct inode **inode) 10771da177e4SLinus Torvalds { 10784ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 107931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 10805a18fff2SAl Viro int need_reval = 1; 10815a18fff2SAl Viro int status = 1; 10829875cf80SDavid Howells int err; 10839875cf80SDavid Howells 10843cac260aSAl Viro /* 1085b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1086b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1087b04f784eSNick Piggin * do the non-racy lookup, below. 1088b04f784eSNick Piggin */ 108931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 109031e6b01fSNick Piggin unsigned seq; 109131e6b01fSNick Piggin *inode = nd->inode; 109231e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 10935a18fff2SAl Viro if (!dentry) 10945a18fff2SAl Viro goto unlazy; 10955a18fff2SAl Viro 109631e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 109731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 109831e6b01fSNick Piggin return -ECHILD; 109931e6b01fSNick Piggin nd->seq = seq; 11005a18fff2SAl Viro 110124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11025a18fff2SAl Viro status = d_revalidate(dentry, nd); 11035a18fff2SAl Viro if (unlikely(status <= 0)) { 11045a18fff2SAl Viro if (status != -ECHILD) 11055a18fff2SAl Viro need_reval = 0; 11065a18fff2SAl Viro goto unlazy; 11075a18fff2SAl Viro } 110824643087SAl Viro } 110944396f4bSJosef Bacik if (unlikely(d_need_lookup(dentry))) 111044396f4bSJosef Bacik goto unlazy; 111131e6b01fSNick Piggin path->mnt = mnt; 111231e6b01fSNick Piggin path->dentry = dentry; 1113d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1114d6e9bd25SAl Viro goto unlazy; 1115d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1116d6e9bd25SAl Viro goto unlazy; 11179875cf80SDavid Howells return 0; 11185a18fff2SAl Viro unlazy: 111919660af7SAl Viro if (unlazy_walk(nd, dentry)) 11205a18fff2SAl Viro return -ECHILD; 11215a18fff2SAl Viro } else { 112231e6b01fSNick Piggin dentry = __d_lookup(parent, name); 112324643087SAl Viro } 11245a18fff2SAl Viro 112544396f4bSJosef Bacik if (dentry && unlikely(d_need_lookup(dentry))) { 112644396f4bSJosef Bacik dput(dentry); 112744396f4bSJosef Bacik dentry = NULL; 112844396f4bSJosef Bacik } 11295a18fff2SAl Viro retry: 11305a18fff2SAl Viro if (unlikely(!dentry)) { 11315a18fff2SAl Viro struct inode *dir = parent->d_inode; 11325a18fff2SAl Viro BUG_ON(nd->inode != dir); 11335a18fff2SAl Viro 11345a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11355a18fff2SAl Viro dentry = d_lookup(parent, name); 11365a18fff2SAl Viro if (likely(!dentry)) { 11375a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 11385a18fff2SAl Viro if (IS_ERR(dentry)) { 11395a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11405a18fff2SAl Viro return PTR_ERR(dentry); 11415a18fff2SAl Viro } 11425a18fff2SAl Viro /* known good */ 11435a18fff2SAl Viro need_reval = 0; 11445a18fff2SAl Viro status = 1; 114544396f4bSJosef Bacik } else if (unlikely(d_need_lookup(dentry))) { 114644396f4bSJosef Bacik dentry = d_inode_lookup(parent, dentry, nd); 114744396f4bSJosef Bacik if (IS_ERR(dentry)) { 114844396f4bSJosef Bacik mutex_unlock(&dir->i_mutex); 114944396f4bSJosef Bacik return PTR_ERR(dentry); 115044396f4bSJosef Bacik } 115144396f4bSJosef Bacik /* known good */ 115244396f4bSJosef Bacik need_reval = 0; 115344396f4bSJosef Bacik status = 1; 11545a18fff2SAl Viro } 11555a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11565a18fff2SAl Viro } 11575a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 11585a18fff2SAl Viro status = d_revalidate(dentry, nd); 11595a18fff2SAl Viro if (unlikely(status <= 0)) { 11605a18fff2SAl Viro if (status < 0) { 11615a18fff2SAl Viro dput(dentry); 11625a18fff2SAl Viro return status; 11635a18fff2SAl Viro } 11645a18fff2SAl Viro if (!d_invalidate(dentry)) { 11655a18fff2SAl Viro dput(dentry); 11665a18fff2SAl Viro dentry = NULL; 11675a18fff2SAl Viro need_reval = 1; 11685a18fff2SAl Viro goto retry; 11695a18fff2SAl Viro } 11705a18fff2SAl Viro } 11715a18fff2SAl Viro 11721da177e4SLinus Torvalds path->mnt = mnt; 11731da177e4SLinus Torvalds path->dentry = dentry; 11749875cf80SDavid Howells err = follow_managed(path, nd->flags); 117589312214SIan Kent if (unlikely(err < 0)) { 117689312214SIan Kent path_put_conditional(path, nd); 11779875cf80SDavid Howells return err; 117889312214SIan Kent } 117931e6b01fSNick Piggin *inode = path->dentry->d_inode; 11801da177e4SLinus Torvalds return 0; 11811da177e4SLinus Torvalds } 11821da177e4SLinus Torvalds 118352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 118452094c8aSAl Viro { 118552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 11864ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 118752094c8aSAl Viro if (err != -ECHILD) 118852094c8aSAl Viro return err; 118919660af7SAl Viro if (unlazy_walk(nd, NULL)) 119052094c8aSAl Viro return -ECHILD; 119152094c8aSAl Viro } 11924ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 119352094c8aSAl Viro } 119452094c8aSAl Viro 11959856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 11969856fa1bSAl Viro { 11979856fa1bSAl Viro if (type == LAST_DOTDOT) { 11989856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 11999856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12009856fa1bSAl Viro return -ECHILD; 12019856fa1bSAl Viro } else 12029856fa1bSAl Viro follow_dotdot(nd); 12039856fa1bSAl Viro } 12049856fa1bSAl Viro return 0; 12059856fa1bSAl Viro } 12069856fa1bSAl Viro 1207951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1208951361f9SAl Viro { 1209951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1210951361f9SAl Viro path_put(&nd->path); 1211951361f9SAl Viro } else { 1212951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12135b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1214951361f9SAl Viro nd->root.mnt = NULL; 1215951361f9SAl Viro rcu_read_unlock(); 1216951361f9SAl Viro br_read_unlock(vfsmount_lock); 1217951361f9SAl Viro } 1218951361f9SAl Viro } 1219951361f9SAl Viro 1220ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1221ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1222ce57dfc1SAl Viro { 1223ce57dfc1SAl Viro struct inode *inode; 1224ce57dfc1SAl Viro int err; 1225ce57dfc1SAl Viro /* 1226ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1227ce57dfc1SAl Viro * to be able to know about the current root directory and 1228ce57dfc1SAl Viro * parent relationships. 1229ce57dfc1SAl Viro */ 1230ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1231ce57dfc1SAl Viro return handle_dots(nd, type); 1232ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1233ce57dfc1SAl Viro if (unlikely(err)) { 1234ce57dfc1SAl Viro terminate_walk(nd); 1235ce57dfc1SAl Viro return err; 1236ce57dfc1SAl Viro } 1237ce57dfc1SAl Viro if (!inode) { 1238ce57dfc1SAl Viro path_to_nameidata(path, nd); 1239ce57dfc1SAl Viro terminate_walk(nd); 1240ce57dfc1SAl Viro return -ENOENT; 1241ce57dfc1SAl Viro } 1242ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 124319660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 124419660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 124519660af7SAl Viro terminate_walk(nd); 1246ce57dfc1SAl Viro return -ECHILD; 124719660af7SAl Viro } 124819660af7SAl Viro } 1249ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1250ce57dfc1SAl Viro return 1; 1251ce57dfc1SAl Viro } 1252ce57dfc1SAl Viro path_to_nameidata(path, nd); 1253ce57dfc1SAl Viro nd->inode = inode; 1254ce57dfc1SAl Viro return 0; 1255ce57dfc1SAl Viro } 1256ce57dfc1SAl Viro 12571da177e4SLinus Torvalds /* 1258b356379aSAl Viro * This limits recursive symlink follows to 8, while 1259b356379aSAl Viro * limiting consecutive symlinks to 40. 1260b356379aSAl Viro * 1261b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1262b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1263b356379aSAl Viro */ 1264b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1265b356379aSAl Viro { 1266b356379aSAl Viro int res; 1267b356379aSAl Viro 1268b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1269b356379aSAl Viro path_put_conditional(path, nd); 1270b356379aSAl Viro path_put(&nd->path); 1271b356379aSAl Viro return -ELOOP; 1272b356379aSAl Viro } 12731a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1274b356379aSAl Viro 1275b356379aSAl Viro nd->depth++; 1276b356379aSAl Viro current->link_count++; 1277b356379aSAl Viro 1278b356379aSAl Viro do { 1279b356379aSAl Viro struct path link = *path; 1280b356379aSAl Viro void *cookie; 1281574197e0SAl Viro 1282574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1283b356379aSAl Viro if (!res) 1284b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1285b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1286574197e0SAl Viro put_link(nd, &link, cookie); 1287b356379aSAl Viro } while (res > 0); 1288b356379aSAl Viro 1289b356379aSAl Viro current->link_count--; 1290b356379aSAl Viro nd->depth--; 1291b356379aSAl Viro return res; 1292b356379aSAl Viro } 1293b356379aSAl Viro 1294b356379aSAl Viro /* 12951da177e4SLinus Torvalds * Name resolution. 1296ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1297ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 12981da177e4SLinus Torvalds * 1299ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1300ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13011da177e4SLinus Torvalds */ 13026de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13031da177e4SLinus Torvalds { 13041da177e4SLinus Torvalds struct path next; 13051da177e4SLinus Torvalds int err; 13061da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13071da177e4SLinus Torvalds 13081da177e4SLinus Torvalds while (*name=='/') 13091da177e4SLinus Torvalds name++; 13101da177e4SLinus Torvalds if (!*name) 1311086e183aSAl Viro return 0; 13121da177e4SLinus Torvalds 13131da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13141da177e4SLinus Torvalds for(;;) { 13151da177e4SLinus Torvalds unsigned long hash; 13161da177e4SLinus Torvalds struct qstr this; 13171da177e4SLinus Torvalds unsigned int c; 1318fe479a58SAl Viro int type; 13191da177e4SLinus Torvalds 1320cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 132152094c8aSAl Viro 132252094c8aSAl Viro err = may_lookup(nd); 13231da177e4SLinus Torvalds if (err) 13241da177e4SLinus Torvalds break; 13251da177e4SLinus Torvalds 13261da177e4SLinus Torvalds this.name = name; 13271da177e4SLinus Torvalds c = *(const unsigned char *)name; 13281da177e4SLinus Torvalds 13291da177e4SLinus Torvalds hash = init_name_hash(); 13301da177e4SLinus Torvalds do { 13311da177e4SLinus Torvalds name++; 13321da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13331da177e4SLinus Torvalds c = *(const unsigned char *)name; 13341da177e4SLinus Torvalds } while (c && (c != '/')); 13351da177e4SLinus Torvalds this.len = name - (const char *) this.name; 13361da177e4SLinus Torvalds this.hash = end_name_hash(hash); 13371da177e4SLinus Torvalds 1338fe479a58SAl Viro type = LAST_NORM; 1339fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1340fe479a58SAl Viro case 2: 134116c2cd71SAl Viro if (this.name[1] == '.') { 1342fe479a58SAl Viro type = LAST_DOTDOT; 134316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 134416c2cd71SAl Viro } 1345fe479a58SAl Viro break; 1346fe479a58SAl Viro case 1: 1347fe479a58SAl Viro type = LAST_DOT; 1348fe479a58SAl Viro } 13495a202bcdSAl Viro if (likely(type == LAST_NORM)) { 13505a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 135116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 13525a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 13535a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 13545a202bcdSAl Viro &this); 13555a202bcdSAl Viro if (err < 0) 13565a202bcdSAl Viro break; 13575a202bcdSAl Viro } 13585a202bcdSAl Viro } 1359fe479a58SAl Viro 13601da177e4SLinus Torvalds /* remove trailing slashes? */ 13611da177e4SLinus Torvalds if (!c) 13621da177e4SLinus Torvalds goto last_component; 13631da177e4SLinus Torvalds while (*++name == '/'); 13641da177e4SLinus Torvalds if (!*name) 1365b356379aSAl Viro goto last_component; 13661da177e4SLinus Torvalds 1367ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1368ce57dfc1SAl Viro if (err < 0) 1369ce57dfc1SAl Viro return err; 1370fe479a58SAl Viro 1371ce57dfc1SAl Viro if (err) { 1372b356379aSAl Viro err = nested_symlink(&next, nd); 13731da177e4SLinus Torvalds if (err) 1374a7472babSAl Viro return err; 137531e6b01fSNick Piggin } 13761da177e4SLinus Torvalds err = -ENOTDIR; 137731e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 13781da177e4SLinus Torvalds break; 13791da177e4SLinus Torvalds continue; 13801da177e4SLinus Torvalds /* here ends the main loop */ 13811da177e4SLinus Torvalds 13821da177e4SLinus Torvalds last_component: 1383f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1384f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1385ce57dfc1SAl Viro nd->last = this; 1386ce57dfc1SAl Viro nd->last_type = type; 1387ce57dfc1SAl Viro return 0; 1388ce57dfc1SAl Viro } 1389951361f9SAl Viro terminate_walk(nd); 13901da177e4SLinus Torvalds return err; 13911da177e4SLinus Torvalds } 13921da177e4SLinus Torvalds 139370e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 139470e9b357SAl Viro struct nameidata *nd, struct file **fp) 139531e6b01fSNick Piggin { 139631e6b01fSNick Piggin int retval = 0; 139731e6b01fSNick Piggin int fput_needed; 139831e6b01fSNick Piggin struct file *file; 139931e6b01fSNick Piggin 140031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 140116c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 140231e6b01fSNick Piggin nd->depth = 0; 14035b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14045b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 140573d049a4SAl Viro if (*name) { 14065b6ca027SAl Viro if (!inode->i_op->lookup) 14075b6ca027SAl Viro return -ENOTDIR; 14085b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14095b6ca027SAl Viro if (retval) 14105b6ca027SAl Viro return retval; 141173d049a4SAl Viro } 14125b6ca027SAl Viro nd->path = nd->root; 14135b6ca027SAl Viro nd->inode = inode; 14145b6ca027SAl Viro if (flags & LOOKUP_RCU) { 14155b6ca027SAl Viro br_read_lock(vfsmount_lock); 14165b6ca027SAl Viro rcu_read_lock(); 14175b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 14185b6ca027SAl Viro } else { 14195b6ca027SAl Viro path_get(&nd->path); 14205b6ca027SAl Viro } 14215b6ca027SAl Viro return 0; 14225b6ca027SAl Viro } 14235b6ca027SAl Viro 142431e6b01fSNick Piggin nd->root.mnt = NULL; 142531e6b01fSNick Piggin 142631e6b01fSNick Piggin if (*name=='/') { 1427e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 142831e6b01fSNick Piggin br_read_lock(vfsmount_lock); 142931e6b01fSNick Piggin rcu_read_lock(); 1430e41f7d4eSAl Viro set_root_rcu(nd); 1431e41f7d4eSAl Viro } else { 1432e41f7d4eSAl Viro set_root(nd); 1433e41f7d4eSAl Viro path_get(&nd->root); 1434e41f7d4eSAl Viro } 143531e6b01fSNick Piggin nd->path = nd->root; 143631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1437e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 143831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1439c28cc364SNick Piggin unsigned seq; 144031e6b01fSNick Piggin 144131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 144231e6b01fSNick Piggin rcu_read_lock(); 144331e6b01fSNick Piggin 1444c28cc364SNick Piggin do { 1445c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 144631e6b01fSNick Piggin nd->path = fs->pwd; 1447c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1448c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1449e41f7d4eSAl Viro } else { 1450e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1451e41f7d4eSAl Viro } 145231e6b01fSNick Piggin } else { 145331e6b01fSNick Piggin struct dentry *dentry; 145431e6b01fSNick Piggin 14551abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 145631e6b01fSNick Piggin retval = -EBADF; 145731e6b01fSNick Piggin if (!file) 145831e6b01fSNick Piggin goto out_fail; 145931e6b01fSNick Piggin 146031e6b01fSNick Piggin dentry = file->f_path.dentry; 146131e6b01fSNick Piggin 1462f52e0c11SAl Viro if (*name) { 146331e6b01fSNick Piggin retval = -ENOTDIR; 146431e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 146531e6b01fSNick Piggin goto fput_fail; 146631e6b01fSNick Piggin 14674ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 146831e6b01fSNick Piggin if (retval) 146931e6b01fSNick Piggin goto fput_fail; 1470f52e0c11SAl Viro } 147131e6b01fSNick Piggin 147231e6b01fSNick Piggin nd->path = file->f_path; 1473e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 147431e6b01fSNick Piggin if (fput_needed) 147570e9b357SAl Viro *fp = file; 1476c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 147731e6b01fSNick Piggin br_read_lock(vfsmount_lock); 147831e6b01fSNick Piggin rcu_read_lock(); 14795590ff0dSUlrich Drepper } else { 14805dd784d0SJan Blunck path_get(&file->f_path); 14815590ff0dSUlrich Drepper fput_light(file, fput_needed); 14821da177e4SLinus Torvalds } 1483e41f7d4eSAl Viro } 1484e41f7d4eSAl Viro 148531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14869b4a9b14SAl Viro return 0; 14872dfdd266SJosef 'Jeff' Sipek 14889b4a9b14SAl Viro fput_fail: 14899b4a9b14SAl Viro fput_light(file, fput_needed); 14909b4a9b14SAl Viro out_fail: 14919b4a9b14SAl Viro return retval; 14929b4a9b14SAl Viro } 14939b4a9b14SAl Viro 1494bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1495bd92d7feSAl Viro { 1496bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1497bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1498bd92d7feSAl Viro 1499bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1500bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1501bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1502bd92d7feSAl Viro } 1503bd92d7feSAl Viro 15049b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1505ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15069b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15079b4a9b14SAl Viro { 150870e9b357SAl Viro struct file *base = NULL; 1509bd92d7feSAl Viro struct path path; 1510bd92d7feSAl Viro int err; 151131e6b01fSNick Piggin 151231e6b01fSNick Piggin /* 151331e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 151431e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 151531e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 151631e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 151731e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 151831e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 151931e6b01fSNick Piggin * analogue, foo_rcu(). 152031e6b01fSNick Piggin * 152131e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 152231e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 152331e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 152431e6b01fSNick Piggin * be able to complete). 152531e6b01fSNick Piggin */ 1526bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1527ee0827cdSAl Viro 1528bd92d7feSAl Viro if (unlikely(err)) 1529bd92d7feSAl Viro return err; 1530ee0827cdSAl Viro 1531ee0827cdSAl Viro current->total_link_count = 0; 1532bd92d7feSAl Viro err = link_path_walk(name, nd); 1533bd92d7feSAl Viro 1534bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1535bd92d7feSAl Viro err = lookup_last(nd, &path); 1536bd92d7feSAl Viro while (err > 0) { 1537bd92d7feSAl Viro void *cookie; 1538bd92d7feSAl Viro struct path link = path; 1539bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1540574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1541bd92d7feSAl Viro if (!err) 1542bd92d7feSAl Viro err = lookup_last(nd, &path); 1543574197e0SAl Viro put_link(nd, &link, cookie); 1544bd92d7feSAl Viro } 1545bd92d7feSAl Viro } 1546ee0827cdSAl Viro 15479f1fafeeSAl Viro if (!err) 15489f1fafeeSAl Viro err = complete_walk(nd); 1549bd92d7feSAl Viro 1550bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1551bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1552bd92d7feSAl Viro path_put(&nd->path); 1553bd23a539SAl Viro err = -ENOTDIR; 1554bd92d7feSAl Viro } 1555bd92d7feSAl Viro } 155616c2cd71SAl Viro 155770e9b357SAl Viro if (base) 155870e9b357SAl Viro fput(base); 1559ee0827cdSAl Viro 15605b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 156131e6b01fSNick Piggin path_put(&nd->root); 156231e6b01fSNick Piggin nd->root.mnt = NULL; 156331e6b01fSNick Piggin } 1564bd92d7feSAl Viro return err; 156531e6b01fSNick Piggin } 156631e6b01fSNick Piggin 1567ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1568ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1569ee0827cdSAl Viro { 1570ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1571ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1572ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1573ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1574ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1575ee0827cdSAl Viro 157631e6b01fSNick Piggin if (likely(!retval)) { 157731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 157831e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 157931e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 158031e6b01fSNick Piggin } 158131e6b01fSNick Piggin } 1582170aa3d0SUlrich Drepper return retval; 15831da177e4SLinus Torvalds } 15841da177e4SLinus Torvalds 1585c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 15865590ff0dSUlrich Drepper { 1587c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 15885590ff0dSUlrich Drepper } 15895590ff0dSUlrich Drepper 1590d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1591d1811465SAl Viro { 1592d1811465SAl Viro struct nameidata nd; 1593d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1594d1811465SAl Viro if (!res) 1595d1811465SAl Viro *path = nd.path; 1596d1811465SAl Viro return res; 1597d1811465SAl Viro } 1598d1811465SAl Viro 159916f18200SJosef 'Jeff' Sipek /** 160016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 160116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 160216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 160316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 160416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 160516f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 160616f18200SJosef 'Jeff' Sipek */ 160716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 160816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 160916f18200SJosef 'Jeff' Sipek struct nameidata *nd) 161016f18200SJosef 'Jeff' Sipek { 16115b6ca027SAl Viro nd->root.dentry = dentry; 16125b6ca027SAl Viro nd->root.mnt = mnt; 16135b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 16145b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 161516f18200SJosef 'Jeff' Sipek } 161616f18200SJosef 'Jeff' Sipek 1617eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1618eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16191da177e4SLinus Torvalds { 162081fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16211da177e4SLinus Torvalds struct dentry *dentry; 16221da177e4SLinus Torvalds int err; 16231da177e4SLinus Torvalds 16244ad5abb3SAl Viro err = inode_permission(inode, MAY_EXEC); 162581fca444SChristoph Hellwig if (err) 162681fca444SChristoph Hellwig return ERR_PTR(err); 16271da177e4SLinus Torvalds 16281da177e4SLinus Torvalds /* 1629b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1630b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1631b04f784eSNick Piggin * a double lookup. 16326e6b1bd1SAl Viro */ 16336e6b1bd1SAl Viro dentry = d_lookup(base, name); 16346e6b1bd1SAl Viro 163544396f4bSJosef Bacik if (dentry && d_need_lookup(dentry)) { 163644396f4bSJosef Bacik /* 163744396f4bSJosef Bacik * __lookup_hash is called with the parent dir's i_mutex already 163844396f4bSJosef Bacik * held, so we are good to go here. 163944396f4bSJosef Bacik */ 164044396f4bSJosef Bacik dentry = d_inode_lookup(base, dentry, nd); 164144396f4bSJosef Bacik if (IS_ERR(dentry)) 164244396f4bSJosef Bacik return dentry; 164344396f4bSJosef Bacik } 164444396f4bSJosef Bacik 1645fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 16466e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 16476e6b1bd1SAl Viro 16481da177e4SLinus Torvalds if (!dentry) 1649baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 16505a202bcdSAl Viro 16511da177e4SLinus Torvalds return dentry; 16521da177e4SLinus Torvalds } 16531da177e4SLinus Torvalds 1654057f6c01SJames Morris /* 1655057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1656057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1657057f6c01SJames Morris * SMP-safe. 1658057f6c01SJames Morris */ 1659a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 16601da177e4SLinus Torvalds { 16614ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 16621da177e4SLinus Torvalds } 16631da177e4SLinus Torvalds 1664eead1911SChristoph Hellwig /** 1665a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1666eead1911SChristoph Hellwig * @name: pathname component to lookup 1667eead1911SChristoph Hellwig * @base: base directory to lookup from 1668eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1669eead1911SChristoph Hellwig * 1670a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1671a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1672eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1673eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1674eead1911SChristoph Hellwig */ 1675057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1676057f6c01SJames Morris { 1677057f6c01SJames Morris struct qstr this; 16786a96ba54SAl Viro unsigned long hash; 16796a96ba54SAl Viro unsigned int c; 1680057f6c01SJames Morris 16812f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 16822f9092e1SDavid Woodhouse 16836a96ba54SAl Viro this.name = name; 16846a96ba54SAl Viro this.len = len; 16856a96ba54SAl Viro if (!len) 16866a96ba54SAl Viro return ERR_PTR(-EACCES); 16876a96ba54SAl Viro 16886a96ba54SAl Viro hash = init_name_hash(); 16896a96ba54SAl Viro while (len--) { 16906a96ba54SAl Viro c = *(const unsigned char *)name++; 16916a96ba54SAl Viro if (c == '/' || c == '\0') 16926a96ba54SAl Viro return ERR_PTR(-EACCES); 16936a96ba54SAl Viro hash = partial_name_hash(c, hash); 16946a96ba54SAl Viro } 16956a96ba54SAl Viro this.hash = end_name_hash(hash); 16965a202bcdSAl Viro /* 16975a202bcdSAl Viro * See if the low-level filesystem might want 16985a202bcdSAl Viro * to use its own hash.. 16995a202bcdSAl Viro */ 17005a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17015a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17025a202bcdSAl Viro if (err < 0) 17035a202bcdSAl Viro return ERR_PTR(err); 17045a202bcdSAl Viro } 1705eead1911SChristoph Hellwig 170649705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1707057f6c01SJames Morris } 1708057f6c01SJames Morris 17092d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 17102d8f3038SAl Viro struct path *path) 17111da177e4SLinus Torvalds { 17122d8f3038SAl Viro struct nameidata nd; 1713f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 17141da177e4SLinus Torvalds int err = PTR_ERR(tmp); 17151da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 17162d8f3038SAl Viro 17172d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 17182d8f3038SAl Viro 17192d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 17201da177e4SLinus Torvalds putname(tmp); 17212d8f3038SAl Viro if (!err) 17222d8f3038SAl Viro *path = nd.path; 17231da177e4SLinus Torvalds } 17241da177e4SLinus Torvalds return err; 17251da177e4SLinus Torvalds } 17261da177e4SLinus Torvalds 17272ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 17282ad94ae6SAl Viro struct nameidata *nd, char **name) 17292ad94ae6SAl Viro { 17302ad94ae6SAl Viro char *s = getname(path); 17312ad94ae6SAl Viro int error; 17322ad94ae6SAl Viro 17332ad94ae6SAl Viro if (IS_ERR(s)) 17342ad94ae6SAl Viro return PTR_ERR(s); 17352ad94ae6SAl Viro 17362ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 17372ad94ae6SAl Viro if (error) 17382ad94ae6SAl Viro putname(s); 17392ad94ae6SAl Viro else 17402ad94ae6SAl Viro *name = s; 17412ad94ae6SAl Viro 17422ad94ae6SAl Viro return error; 17432ad94ae6SAl Viro } 17442ad94ae6SAl Viro 17451da177e4SLinus Torvalds /* 17461da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 17471da177e4SLinus Torvalds * minimal. 17481da177e4SLinus Torvalds */ 17491da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 17501da177e4SLinus Torvalds { 1751da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1752da9592edSDavid Howells 17531da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 17541da177e4SLinus Torvalds return 0; 1755e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1756e795b717SSerge E. Hallyn goto other_userns; 1757da9592edSDavid Howells if (inode->i_uid == fsuid) 17581da177e4SLinus Torvalds return 0; 1759da9592edSDavid Howells if (dir->i_uid == fsuid) 17601da177e4SLinus Torvalds return 0; 1761e795b717SSerge E. Hallyn 1762e795b717SSerge E. Hallyn other_userns: 1763e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 17641da177e4SLinus Torvalds } 17651da177e4SLinus Torvalds 17661da177e4SLinus Torvalds /* 17671da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 17681da177e4SLinus Torvalds * whether the type of victim is right. 17691da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 17701da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 17711da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 17721da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 17731da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 17741da177e4SLinus Torvalds * a. be owner of dir, or 17751da177e4SLinus Torvalds * b. be owner of victim, or 17761da177e4SLinus Torvalds * c. have CAP_FOWNER capability 17771da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 17781da177e4SLinus Torvalds * links pointing to it. 17791da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 17801da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 17811da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 17821da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 17831da177e4SLinus Torvalds * nfs_async_unlink(). 17841da177e4SLinus Torvalds */ 1785858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 17861da177e4SLinus Torvalds { 17871da177e4SLinus Torvalds int error; 17881da177e4SLinus Torvalds 17891da177e4SLinus Torvalds if (!victim->d_inode) 17901da177e4SLinus Torvalds return -ENOENT; 17911da177e4SLinus Torvalds 17921da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1793cccc6bbaSAl Viro audit_inode_child(victim, dir); 17941da177e4SLinus Torvalds 1795f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 17961da177e4SLinus Torvalds if (error) 17971da177e4SLinus Torvalds return error; 17981da177e4SLinus Torvalds if (IS_APPEND(dir)) 17991da177e4SLinus Torvalds return -EPERM; 18001da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1801f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18021da177e4SLinus Torvalds return -EPERM; 18031da177e4SLinus Torvalds if (isdir) { 18041da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18051da177e4SLinus Torvalds return -ENOTDIR; 18061da177e4SLinus Torvalds if (IS_ROOT(victim)) 18071da177e4SLinus Torvalds return -EBUSY; 18081da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18091da177e4SLinus Torvalds return -EISDIR; 18101da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18111da177e4SLinus Torvalds return -ENOENT; 18121da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 18131da177e4SLinus Torvalds return -EBUSY; 18141da177e4SLinus Torvalds return 0; 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds 18171da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 18181da177e4SLinus Torvalds * dir. 18191da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 18201da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 18211da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 18221da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 18231da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 18241da177e4SLinus Torvalds */ 1825a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 18261da177e4SLinus Torvalds { 18271da177e4SLinus Torvalds if (child->d_inode) 18281da177e4SLinus Torvalds return -EEXIST; 18291da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18301da177e4SLinus Torvalds return -ENOENT; 1831f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 18321da177e4SLinus Torvalds } 18331da177e4SLinus Torvalds 18341da177e4SLinus Torvalds /* 18351da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 18361da177e4SLinus Torvalds */ 18371da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 18381da177e4SLinus Torvalds { 18391da177e4SLinus Torvalds struct dentry *p; 18401da177e4SLinus Torvalds 18411da177e4SLinus Torvalds if (p1 == p2) { 1842f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 18431da177e4SLinus Torvalds return NULL; 18441da177e4SLinus Torvalds } 18451da177e4SLinus Torvalds 1846a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18471da177e4SLinus Torvalds 1848e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1849e2761a11SOGAWA Hirofumi if (p) { 1850f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1851f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 18521da177e4SLinus Torvalds return p; 18531da177e4SLinus Torvalds } 18541da177e4SLinus Torvalds 1855e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1856e2761a11SOGAWA Hirofumi if (p) { 1857f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1858f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 18591da177e4SLinus Torvalds return p; 18601da177e4SLinus Torvalds } 18611da177e4SLinus Torvalds 1862f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1863f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 18641da177e4SLinus Torvalds return NULL; 18651da177e4SLinus Torvalds } 18661da177e4SLinus Torvalds 18671da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 18681da177e4SLinus Torvalds { 18691b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 18701da177e4SLinus Torvalds if (p1 != p2) { 18711b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1872a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18731da177e4SLinus Torvalds } 18741da177e4SLinus Torvalds } 18751da177e4SLinus Torvalds 18761da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 18771da177e4SLinus Torvalds struct nameidata *nd) 18781da177e4SLinus Torvalds { 1879a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 18801da177e4SLinus Torvalds 18811da177e4SLinus Torvalds if (error) 18821da177e4SLinus Torvalds return error; 18831da177e4SLinus Torvalds 1884acfa4380SAl Viro if (!dir->i_op->create) 18851da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 18861da177e4SLinus Torvalds mode &= S_IALLUGO; 18871da177e4SLinus Torvalds mode |= S_IFREG; 18881da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 18891da177e4SLinus Torvalds if (error) 18901da177e4SLinus Torvalds return error; 18911da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1892a74574aaSStephen Smalley if (!error) 1893f38aa942SAmy Griffis fsnotify_create(dir, dentry); 18941da177e4SLinus Torvalds return error; 18951da177e4SLinus Torvalds } 18961da177e4SLinus Torvalds 189773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 18981da177e4SLinus Torvalds { 18993fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19001da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19011da177e4SLinus Torvalds int error; 19021da177e4SLinus Torvalds 1903bcda7652SAl Viro /* O_PATH? */ 1904bcda7652SAl Viro if (!acc_mode) 1905bcda7652SAl Viro return 0; 1906bcda7652SAl Viro 19071da177e4SLinus Torvalds if (!inode) 19081da177e4SLinus Torvalds return -ENOENT; 19091da177e4SLinus Torvalds 1910c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1911c8fe8f30SChristoph Hellwig case S_IFLNK: 19121da177e4SLinus Torvalds return -ELOOP; 1913c8fe8f30SChristoph Hellwig case S_IFDIR: 1914c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 19151da177e4SLinus Torvalds return -EISDIR; 1916c8fe8f30SChristoph Hellwig break; 1917c8fe8f30SChristoph Hellwig case S_IFBLK: 1918c8fe8f30SChristoph Hellwig case S_IFCHR: 19193fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 19201da177e4SLinus Torvalds return -EACCES; 1921c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1922c8fe8f30SChristoph Hellwig case S_IFIFO: 1923c8fe8f30SChristoph Hellwig case S_IFSOCK: 19241da177e4SLinus Torvalds flag &= ~O_TRUNC; 1925c8fe8f30SChristoph Hellwig break; 19264a3fd211SDave Hansen } 1927b41572e9SDave Hansen 19283fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1929b41572e9SDave Hansen if (error) 1930b41572e9SDave Hansen return error; 19316146f0d5SMimi Zohar 19321da177e4SLinus Torvalds /* 19331da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 19341da177e4SLinus Torvalds */ 19351da177e4SLinus Torvalds if (IS_APPEND(inode)) { 19368737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 19377715b521SAl Viro return -EPERM; 19381da177e4SLinus Torvalds if (flag & O_TRUNC) 19397715b521SAl Viro return -EPERM; 19401da177e4SLinus Torvalds } 19411da177e4SLinus Torvalds 19421da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 19432e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 19447715b521SAl Viro return -EPERM; 19451da177e4SLinus Torvalds 19461da177e4SLinus Torvalds /* 19471da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 19481da177e4SLinus Torvalds */ 1949b65a9cfcSAl Viro return break_lease(inode, flag); 19507715b521SAl Viro } 19517715b521SAl Viro 1952e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 19537715b521SAl Viro { 1954e1181ee6SJeff Layton struct path *path = &filp->f_path; 19557715b521SAl Viro struct inode *inode = path->dentry->d_inode; 19567715b521SAl Viro int error = get_write_access(inode); 19571da177e4SLinus Torvalds if (error) 19587715b521SAl Viro return error; 19591da177e4SLinus Torvalds /* 19601da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 19611da177e4SLinus Torvalds */ 19621da177e4SLinus Torvalds error = locks_verify_locked(inode); 1963be6d3e56SKentaro Takeda if (!error) 1964ea0d3ab2STetsuo Handa error = security_path_truncate(path); 19651da177e4SLinus Torvalds if (!error) { 19667715b521SAl Viro error = do_truncate(path->dentry, 0, 1967d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1968e1181ee6SJeff Layton filp); 19691da177e4SLinus Torvalds } 19701da177e4SLinus Torvalds put_write_access(inode); 1971acd0c935SMimi Zohar return error; 19721da177e4SLinus Torvalds } 19731da177e4SLinus Torvalds 1974d57999e1SDave Hansen /* 1975d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1976d57999e1SDave Hansen * 00 - read-only 1977d57999e1SDave Hansen * 01 - write-only 1978d57999e1SDave Hansen * 10 - read-write 1979d57999e1SDave Hansen * 11 - special 1980d57999e1SDave Hansen * it is changed into 1981d57999e1SDave Hansen * 00 - no permissions needed 1982d57999e1SDave Hansen * 01 - read-permission 1983d57999e1SDave Hansen * 10 - write-permission 1984d57999e1SDave Hansen * 11 - read-write 1985d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1986d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1987d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1988d57999e1SDave Hansen * later). 1989d57999e1SDave Hansen * 1990d57999e1SDave Hansen */ 1991d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1992d57999e1SDave Hansen { 1993d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1994d57999e1SDave Hansen flag++; 1995d57999e1SDave Hansen return flag; 1996d57999e1SDave Hansen } 1997d57999e1SDave Hansen 199831e6b01fSNick Piggin /* 1999fe2d35ffSAl Viro * Handle the last step of open() 200031e6b01fSNick Piggin */ 2001fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2002c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2003fb1cc555SAl Viro { 2004a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20056c0d46c4SAl Viro struct dentry *dentry; 2006ca344a89SAl Viro int open_flag = op->open_flag; 20076c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2008ca344a89SAl Viro int want_write = 0; 2009bcda7652SAl Viro int acc_mode = op->acc_mode; 2010fb1cc555SAl Viro struct file *filp; 201116c2cd71SAl Viro int error; 2012fb1cc555SAl Viro 2013c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2014c3e380b0SAl Viro nd->flags |= op->intent; 2015c3e380b0SAl Viro 20161f36f774SAl Viro switch (nd->last_type) { 20171f36f774SAl Viro case LAST_DOTDOT: 2018176306f5SNeil Brown case LAST_DOT: 2019fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2020fe2d35ffSAl Viro if (error) 2021fe2d35ffSAl Viro return ERR_PTR(error); 20221f36f774SAl Viro /* fallthrough */ 20231f36f774SAl Viro case LAST_ROOT: 20249f1fafeeSAl Viro error = complete_walk(nd); 202516c2cd71SAl Viro if (error) 20269f1fafeeSAl Viro return ERR_PTR(error); 2027fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2028ca344a89SAl Viro if (open_flag & O_CREAT) { 202916c2cd71SAl Viro error = -EISDIR; 20301f36f774SAl Viro goto exit; 2031fe2d35ffSAl Viro } 2032fe2d35ffSAl Viro goto ok; 20331f36f774SAl Viro case LAST_BIND: 20349f1fafeeSAl Viro error = complete_walk(nd); 203516c2cd71SAl Viro if (error) 20369f1fafeeSAl Viro return ERR_PTR(error); 20371f36f774SAl Viro audit_inode(pathname, dir); 20381f36f774SAl Viro goto ok; 20391f36f774SAl Viro } 2040a2c36b45SAl Viro 2041ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2042bcda7652SAl Viro int symlink_ok = 0; 2043fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2044fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2045bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2046bcda7652SAl Viro symlink_ok = 1; 2047fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2048ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2049ce57dfc1SAl Viro !symlink_ok); 2050ce57dfc1SAl Viro if (error < 0) 2051fe2d35ffSAl Viro return ERR_PTR(error); 2052ce57dfc1SAl Viro if (error) /* symlink */ 2053fe2d35ffSAl Viro return NULL; 2054fe2d35ffSAl Viro /* sayonara */ 20559f1fafeeSAl Viro error = complete_walk(nd); 20569f1fafeeSAl Viro if (error) 2057fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2058fe2d35ffSAl Viro 2059fe2d35ffSAl Viro error = -ENOTDIR; 2060fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2061ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2062fe2d35ffSAl Viro goto exit; 2063fe2d35ffSAl Viro } 2064fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2065fe2d35ffSAl Viro goto ok; 2066fe2d35ffSAl Viro } 2067fe2d35ffSAl Viro 2068fe2d35ffSAl Viro /* create side of things */ 20699f1fafeeSAl Viro error = complete_walk(nd); 20709f1fafeeSAl Viro if (error) 20719f1fafeeSAl Viro return ERR_PTR(error); 2072fe2d35ffSAl Viro 2073fe2d35ffSAl Viro audit_inode(pathname, dir); 207416c2cd71SAl Viro error = -EISDIR; 20751f36f774SAl Viro /* trailing slashes? */ 207631e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 20771f36f774SAl Viro goto exit; 20781f36f774SAl Viro 2079a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2080a1e28038SAl Viro 20816c0d46c4SAl Viro dentry = lookup_hash(nd); 20826c0d46c4SAl Viro error = PTR_ERR(dentry); 20836c0d46c4SAl Viro if (IS_ERR(dentry)) { 2084fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2085fb1cc555SAl Viro goto exit; 2086fb1cc555SAl Viro } 2087fb1cc555SAl Viro 20886c0d46c4SAl Viro path->dentry = dentry; 20896c0d46c4SAl Viro path->mnt = nd->path.mnt; 20906c0d46c4SAl Viro 2091fb1cc555SAl Viro /* Negative dentry, just create the file */ 20926c0d46c4SAl Viro if (!dentry->d_inode) { 20936c0d46c4SAl Viro int mode = op->mode; 20946c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 20956c0d46c4SAl Viro mode &= ~current_umask(); 2096fb1cc555SAl Viro /* 2097fb1cc555SAl Viro * This write is needed to ensure that a 20986c0d46c4SAl Viro * rw->ro transition does not occur between 2099fb1cc555SAl Viro * the time when the file is created and when 2100fb1cc555SAl Viro * a permanent write count is taken through 2101fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2102fb1cc555SAl Viro */ 2103fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2104fb1cc555SAl Viro if (error) 2105fb1cc555SAl Viro goto exit_mutex_unlock; 2106ca344a89SAl Viro want_write = 1; 21079b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2108ca344a89SAl Viro open_flag &= ~O_TRUNC; 21096c0d46c4SAl Viro will_truncate = 0; 2110bcda7652SAl Viro acc_mode = MAY_OPEN; 21116c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 21126c0d46c4SAl Viro if (error) 21136c0d46c4SAl Viro goto exit_mutex_unlock; 21146c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 21156c0d46c4SAl Viro if (error) 21166c0d46c4SAl Viro goto exit_mutex_unlock; 21176c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 21186c0d46c4SAl Viro dput(nd->path.dentry); 21196c0d46c4SAl Viro nd->path.dentry = dentry; 2120ca344a89SAl Viro goto common; 2121fb1cc555SAl Viro } 2122fb1cc555SAl Viro 2123fb1cc555SAl Viro /* 2124fb1cc555SAl Viro * It already exists. 2125fb1cc555SAl Viro */ 2126fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2127fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2128fb1cc555SAl Viro 2129fb1cc555SAl Viro error = -EEXIST; 2130ca344a89SAl Viro if (open_flag & O_EXCL) 2131fb1cc555SAl Viro goto exit_dput; 2132fb1cc555SAl Viro 21339875cf80SDavid Howells error = follow_managed(path, nd->flags); 21349875cf80SDavid Howells if (error < 0) 2135fb1cc555SAl Viro goto exit_dput; 2136fb1cc555SAl Viro 2137fb1cc555SAl Viro error = -ENOENT; 2138fb1cc555SAl Viro if (!path->dentry->d_inode) 2139fb1cc555SAl Viro goto exit_dput; 21409e67f361SAl Viro 21419e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2142fb1cc555SAl Viro return NULL; 2143fb1cc555SAl Viro 2144fb1cc555SAl Viro path_to_nameidata(path, nd); 214531e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2146fb1cc555SAl Viro error = -EISDIR; 214731e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2148fb1cc555SAl Viro goto exit; 214967ee3ad2SAl Viro ok: 21506c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 21516c0d46c4SAl Viro will_truncate = 0; 21526c0d46c4SAl Viro 21530f9d1a10SAl Viro if (will_truncate) { 21540f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 21550f9d1a10SAl Viro if (error) 21560f9d1a10SAl Viro goto exit; 2157ca344a89SAl Viro want_write = 1; 21580f9d1a10SAl Viro } 2159ca344a89SAl Viro common: 2160bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2161ca344a89SAl Viro if (error) 21620f9d1a10SAl Viro goto exit; 21630f9d1a10SAl Viro filp = nameidata_to_filp(nd); 21640f9d1a10SAl Viro if (!IS_ERR(filp)) { 21650f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 21660f9d1a10SAl Viro if (error) { 21670f9d1a10SAl Viro fput(filp); 21680f9d1a10SAl Viro filp = ERR_PTR(error); 21690f9d1a10SAl Viro } 21700f9d1a10SAl Viro } 21710f9d1a10SAl Viro if (!IS_ERR(filp)) { 21720f9d1a10SAl Viro if (will_truncate) { 21730f9d1a10SAl Viro error = handle_truncate(filp); 21740f9d1a10SAl Viro if (error) { 21750f9d1a10SAl Viro fput(filp); 21760f9d1a10SAl Viro filp = ERR_PTR(error); 21770f9d1a10SAl Viro } 21780f9d1a10SAl Viro } 21790f9d1a10SAl Viro } 2180ca344a89SAl Viro out: 2181ca344a89SAl Viro if (want_write) 21820f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 21830f9d1a10SAl Viro path_put(&nd->path); 2184fb1cc555SAl Viro return filp; 2185fb1cc555SAl Viro 2186fb1cc555SAl Viro exit_mutex_unlock: 2187fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2188fb1cc555SAl Viro exit_dput: 2189fb1cc555SAl Viro path_put_conditional(path, nd); 2190fb1cc555SAl Viro exit: 2191ca344a89SAl Viro filp = ERR_PTR(error); 2192ca344a89SAl Viro goto out; 2193fb1cc555SAl Viro } 2194fb1cc555SAl Viro 219513aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 219673d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 21971da177e4SLinus Torvalds { 2198fe2d35ffSAl Viro struct file *base = NULL; 21994a3fd211SDave Hansen struct file *filp; 22009850c056SAl Viro struct path path; 220113aab428SAl Viro int error; 220231e6b01fSNick Piggin 220331e6b01fSNick Piggin filp = get_empty_filp(); 220431e6b01fSNick Piggin if (!filp) 220531e6b01fSNick Piggin return ERR_PTR(-ENFILE); 220631e6b01fSNick Piggin 220747c805dcSAl Viro filp->f_flags = op->open_flag; 220873d049a4SAl Viro nd->intent.open.file = filp; 220973d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 221073d049a4SAl Viro nd->intent.open.create_mode = op->mode; 221131e6b01fSNick Piggin 221273d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 221331e6b01fSNick Piggin if (unlikely(error)) 221413aab428SAl Viro goto out_filp; 221531e6b01fSNick Piggin 2216fe2d35ffSAl Viro current->total_link_count = 0; 221773d049a4SAl Viro error = link_path_walk(pathname, nd); 221831e6b01fSNick Piggin if (unlikely(error)) 221931e6b01fSNick Piggin goto out_filp; 22201da177e4SLinus Torvalds 222173d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2222806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 22237b9337aaSNick Piggin struct path link = path; 2224def4af30SAl Viro void *cookie; 2225574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 222673d049a4SAl Viro path_put_conditional(&path, nd); 222773d049a4SAl Viro path_put(&nd->path); 222840b39136SAl Viro filp = ERR_PTR(-ELOOP); 222940b39136SAl Viro break; 223040b39136SAl Viro } 223173d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 223273d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2233574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2234c3e380b0SAl Viro if (unlikely(error)) 2235f1afe9efSAl Viro filp = ERR_PTR(error); 2236c3e380b0SAl Viro else 223773d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2238574197e0SAl Viro put_link(nd, &link, cookie); 2239806b681cSAl Viro } 224010fa8e62SAl Viro out: 224173d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 224273d049a4SAl Viro path_put(&nd->root); 2243fe2d35ffSAl Viro if (base) 2244fe2d35ffSAl Viro fput(base); 224573d049a4SAl Viro release_open_intent(nd); 224610fa8e62SAl Viro return filp; 22471da177e4SLinus Torvalds 224831e6b01fSNick Piggin out_filp: 224910fa8e62SAl Viro filp = ERR_PTR(error); 225010fa8e62SAl Viro goto out; 2251de459215SKirill Korotaev } 22521da177e4SLinus Torvalds 225313aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 225413aab428SAl Viro const struct open_flags *op, int flags) 225513aab428SAl Viro { 225673d049a4SAl Viro struct nameidata nd; 225713aab428SAl Viro struct file *filp; 225813aab428SAl Viro 225973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 226013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 226173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 226213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 226373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 226413aab428SAl Viro return filp; 226513aab428SAl Viro } 226613aab428SAl Viro 226773d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 226873d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 226973d049a4SAl Viro { 227073d049a4SAl Viro struct nameidata nd; 227173d049a4SAl Viro struct file *file; 227273d049a4SAl Viro 227373d049a4SAl Viro nd.root.mnt = mnt; 227473d049a4SAl Viro nd.root.dentry = dentry; 227573d049a4SAl Viro 227673d049a4SAl Viro flags |= LOOKUP_ROOT; 227773d049a4SAl Viro 2278bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 227973d049a4SAl Viro return ERR_PTR(-ELOOP); 228073d049a4SAl Viro 228173d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 228273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 228373d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 228473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 228573d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 228673d049a4SAl Viro return file; 228773d049a4SAl Viro } 228873d049a4SAl Viro 22891da177e4SLinus Torvalds /** 22901da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 22911da177e4SLinus Torvalds * @nd: nameidata info 22921da177e4SLinus Torvalds * @is_dir: directory flag 22931da177e4SLinus Torvalds * 22941da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 22951da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2296c663e5d8SChristoph Hellwig * 22974ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 22981da177e4SLinus Torvalds */ 22991da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23001da177e4SLinus Torvalds { 2301c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23021da177e4SLinus Torvalds 23034ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2304c663e5d8SChristoph Hellwig /* 2305c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2306c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2307c663e5d8SChristoph Hellwig */ 23081da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23091da177e4SLinus Torvalds goto fail; 23101da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 23113516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2312a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2313c663e5d8SChristoph Hellwig 2314c663e5d8SChristoph Hellwig /* 2315c663e5d8SChristoph Hellwig * Do the final lookup. 2316c663e5d8SChristoph Hellwig */ 231749705b77SChristoph Hellwig dentry = lookup_hash(nd); 23181da177e4SLinus Torvalds if (IS_ERR(dentry)) 23191da177e4SLinus Torvalds goto fail; 2320c663e5d8SChristoph Hellwig 2321e9baf6e5SAl Viro if (dentry->d_inode) 2322e9baf6e5SAl Viro goto eexist; 2323c663e5d8SChristoph Hellwig /* 2324c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2325c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2326c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2327c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2328c663e5d8SChristoph Hellwig */ 2329e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 23301da177e4SLinus Torvalds dput(dentry); 23311da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2332e9baf6e5SAl Viro } 2333e9baf6e5SAl Viro return dentry; 2334e9baf6e5SAl Viro eexist: 2335e9baf6e5SAl Viro dput(dentry); 2336e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 23371da177e4SLinus Torvalds fail: 23381da177e4SLinus Torvalds return dentry; 23391da177e4SLinus Torvalds } 2340f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 23411da177e4SLinus Torvalds 23421da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 23431da177e4SLinus Torvalds { 2344a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23451da177e4SLinus Torvalds 23461da177e4SLinus Torvalds if (error) 23471da177e4SLinus Torvalds return error; 23481da177e4SLinus Torvalds 2349e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2350e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 23511da177e4SLinus Torvalds return -EPERM; 23521da177e4SLinus Torvalds 2353acfa4380SAl Viro if (!dir->i_op->mknod) 23541da177e4SLinus Torvalds return -EPERM; 23551da177e4SLinus Torvalds 235608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 235708ce5f16SSerge E. Hallyn if (error) 235808ce5f16SSerge E. Hallyn return error; 235908ce5f16SSerge E. Hallyn 23601da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 23611da177e4SLinus Torvalds if (error) 23621da177e4SLinus Torvalds return error; 23631da177e4SLinus Torvalds 23641da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2365a74574aaSStephen Smalley if (!error) 2366f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23671da177e4SLinus Torvalds return error; 23681da177e4SLinus Torvalds } 23691da177e4SLinus Torvalds 2370463c3197SDave Hansen static int may_mknod(mode_t mode) 2371463c3197SDave Hansen { 2372463c3197SDave Hansen switch (mode & S_IFMT) { 2373463c3197SDave Hansen case S_IFREG: 2374463c3197SDave Hansen case S_IFCHR: 2375463c3197SDave Hansen case S_IFBLK: 2376463c3197SDave Hansen case S_IFIFO: 2377463c3197SDave Hansen case S_IFSOCK: 2378463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2379463c3197SDave Hansen return 0; 2380463c3197SDave Hansen case S_IFDIR: 2381463c3197SDave Hansen return -EPERM; 2382463c3197SDave Hansen default: 2383463c3197SDave Hansen return -EINVAL; 2384463c3197SDave Hansen } 2385463c3197SDave Hansen } 2386463c3197SDave Hansen 23872e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 23882e4d0924SHeiko Carstens unsigned, dev) 23891da177e4SLinus Torvalds { 23902ad94ae6SAl Viro int error; 23911da177e4SLinus Torvalds char *tmp; 23921da177e4SLinus Torvalds struct dentry *dentry; 23931da177e4SLinus Torvalds struct nameidata nd; 23941da177e4SLinus Torvalds 23951da177e4SLinus Torvalds if (S_ISDIR(mode)) 23961da177e4SLinus Torvalds return -EPERM; 23971da177e4SLinus Torvalds 23982ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 23991da177e4SLinus Torvalds if (error) 24002ad94ae6SAl Viro return error; 24012ad94ae6SAl Viro 24021da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2403463c3197SDave Hansen if (IS_ERR(dentry)) { 24041da177e4SLinus Torvalds error = PTR_ERR(dentry); 2405463c3197SDave Hansen goto out_unlock; 2406463c3197SDave Hansen } 24074ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2408ce3b0f8dSAl Viro mode &= ~current_umask(); 2409463c3197SDave Hansen error = may_mknod(mode); 2410463c3197SDave Hansen if (error) 2411463c3197SDave Hansen goto out_dput; 2412463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2413463c3197SDave Hansen if (error) 2414463c3197SDave Hansen goto out_dput; 2415be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2416be6d3e56SKentaro Takeda if (error) 2417be6d3e56SKentaro Takeda goto out_drop_write; 24181da177e4SLinus Torvalds switch (mode & S_IFMT) { 24191da177e4SLinus Torvalds case 0: case S_IFREG: 24204ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 24211da177e4SLinus Torvalds break; 24221da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 24234ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 24241da177e4SLinus Torvalds new_decode_dev(dev)); 24251da177e4SLinus Torvalds break; 24261da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 24274ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 24281da177e4SLinus Torvalds break; 24291da177e4SLinus Torvalds } 2430be6d3e56SKentaro Takeda out_drop_write: 2431463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2432463c3197SDave Hansen out_dput: 24331da177e4SLinus Torvalds dput(dentry); 2434463c3197SDave Hansen out_unlock: 24354ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24361d957f9bSJan Blunck path_put(&nd.path); 24371da177e4SLinus Torvalds putname(tmp); 24381da177e4SLinus Torvalds 24391da177e4SLinus Torvalds return error; 24401da177e4SLinus Torvalds } 24411da177e4SLinus Torvalds 24423480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 24435590ff0dSUlrich Drepper { 24445590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 24455590ff0dSUlrich Drepper } 24465590ff0dSUlrich Drepper 24471da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 24481da177e4SLinus Torvalds { 2449a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds if (error) 24521da177e4SLinus Torvalds return error; 24531da177e4SLinus Torvalds 2454acfa4380SAl Viro if (!dir->i_op->mkdir) 24551da177e4SLinus Torvalds return -EPERM; 24561da177e4SLinus Torvalds 24571da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 24581da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 24591da177e4SLinus Torvalds if (error) 24601da177e4SLinus Torvalds return error; 24611da177e4SLinus Torvalds 24621da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2463a74574aaSStephen Smalley if (!error) 2464f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 24651da177e4SLinus Torvalds return error; 24661da177e4SLinus Torvalds } 24671da177e4SLinus Torvalds 24682e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 24691da177e4SLinus Torvalds { 24701da177e4SLinus Torvalds int error = 0; 24711da177e4SLinus Torvalds char * tmp; 24726902d925SDave Hansen struct dentry *dentry; 24736902d925SDave Hansen struct nameidata nd; 24741da177e4SLinus Torvalds 24752ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 24762ad94ae6SAl Viro if (error) 24776902d925SDave Hansen goto out_err; 24781da177e4SLinus Torvalds 24791da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 24801da177e4SLinus Torvalds error = PTR_ERR(dentry); 24816902d925SDave Hansen if (IS_ERR(dentry)) 24826902d925SDave Hansen goto out_unlock; 24836902d925SDave Hansen 24844ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2485ce3b0f8dSAl Viro mode &= ~current_umask(); 2486463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2487463c3197SDave Hansen if (error) 2488463c3197SDave Hansen goto out_dput; 2489be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2490be6d3e56SKentaro Takeda if (error) 2491be6d3e56SKentaro Takeda goto out_drop_write; 24924ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2493be6d3e56SKentaro Takeda out_drop_write: 2494463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2495463c3197SDave Hansen out_dput: 24961da177e4SLinus Torvalds dput(dentry); 24976902d925SDave Hansen out_unlock: 24984ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24991d957f9bSJan Blunck path_put(&nd.path); 25001da177e4SLinus Torvalds putname(tmp); 25016902d925SDave Hansen out_err: 25021da177e4SLinus Torvalds return error; 25031da177e4SLinus Torvalds } 25041da177e4SLinus Torvalds 25053cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25065590ff0dSUlrich Drepper { 25075590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25085590ff0dSUlrich Drepper } 25095590ff0dSUlrich Drepper 25101da177e4SLinus Torvalds /* 2511a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2512a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2513a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2514a71905f0SSage Weil * then we drop the dentry now. 25151da177e4SLinus Torvalds * 25161da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 25171da177e4SLinus Torvalds * do a 25181da177e4SLinus Torvalds * 25191da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 25201da177e4SLinus Torvalds * return -EBUSY; 25211da177e4SLinus Torvalds * 25221da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 25231da177e4SLinus Torvalds * that is still in use by something else.. 25241da177e4SLinus Torvalds */ 25251da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 25261da177e4SLinus Torvalds { 25271da177e4SLinus Torvalds shrink_dcache_parent(dentry); 25281da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 252964252c75SSage Weil if (dentry->d_count == 1) 25301da177e4SLinus Torvalds __d_drop(dentry); 25311da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 25321da177e4SLinus Torvalds } 25331da177e4SLinus Torvalds 25341da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 25351da177e4SLinus Torvalds { 25361da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 25371da177e4SLinus Torvalds 25381da177e4SLinus Torvalds if (error) 25391da177e4SLinus Torvalds return error; 25401da177e4SLinus Torvalds 2541acfa4380SAl Viro if (!dir->i_op->rmdir) 25421da177e4SLinus Torvalds return -EPERM; 25431da177e4SLinus Torvalds 25441b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2545912dbc15SSage Weil 25461da177e4SLinus Torvalds error = -EBUSY; 2547912dbc15SSage Weil if (d_mountpoint(dentry)) 2548912dbc15SSage Weil goto out; 2549912dbc15SSage Weil 25501da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2551912dbc15SSage Weil if (error) 2552912dbc15SSage Weil goto out; 2553912dbc15SSage Weil 25543cebde24SSage Weil shrink_dcache_parent(dentry); 25551da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2556912dbc15SSage Weil if (error) 2557912dbc15SSage Weil goto out; 2558912dbc15SSage Weil 25591da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2560d83c49f3SAl Viro dont_mount(dentry); 25611da177e4SLinus Torvalds 2562912dbc15SSage Weil out: 2563912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 2564912dbc15SSage Weil if (!error) 2565912dbc15SSage Weil d_delete(dentry); 25661da177e4SLinus Torvalds return error; 25671da177e4SLinus Torvalds } 25681da177e4SLinus Torvalds 25695590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 25701da177e4SLinus Torvalds { 25711da177e4SLinus Torvalds int error = 0; 25721da177e4SLinus Torvalds char * name; 25731da177e4SLinus Torvalds struct dentry *dentry; 25741da177e4SLinus Torvalds struct nameidata nd; 25751da177e4SLinus Torvalds 25762ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 25771da177e4SLinus Torvalds if (error) 25782ad94ae6SAl Viro return error; 25791da177e4SLinus Torvalds 25801da177e4SLinus Torvalds switch(nd.last_type) { 25811da177e4SLinus Torvalds case LAST_DOTDOT: 25821da177e4SLinus Torvalds error = -ENOTEMPTY; 25831da177e4SLinus Torvalds goto exit1; 25841da177e4SLinus Torvalds case LAST_DOT: 25851da177e4SLinus Torvalds error = -EINVAL; 25861da177e4SLinus Torvalds goto exit1; 25871da177e4SLinus Torvalds case LAST_ROOT: 25881da177e4SLinus Torvalds error = -EBUSY; 25891da177e4SLinus Torvalds goto exit1; 25901da177e4SLinus Torvalds } 25910612d9fbSOGAWA Hirofumi 25920612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 25930612d9fbSOGAWA Hirofumi 25944ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 259549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 25961da177e4SLinus Torvalds error = PTR_ERR(dentry); 25976902d925SDave Hansen if (IS_ERR(dentry)) 25986902d925SDave Hansen goto exit2; 2599e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2600e6bc45d6STheodore Ts'o error = -ENOENT; 2601e6bc45d6STheodore Ts'o goto exit3; 2602e6bc45d6STheodore Ts'o } 26030622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26040622753bSDave Hansen if (error) 26050622753bSDave Hansen goto exit3; 2606be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2607be6d3e56SKentaro Takeda if (error) 2608be6d3e56SKentaro Takeda goto exit4; 26094ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2610be6d3e56SKentaro Takeda exit4: 26110622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26120622753bSDave Hansen exit3: 26131da177e4SLinus Torvalds dput(dentry); 26146902d925SDave Hansen exit2: 26154ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26161da177e4SLinus Torvalds exit1: 26171d957f9bSJan Blunck path_put(&nd.path); 26181da177e4SLinus Torvalds putname(name); 26191da177e4SLinus Torvalds return error; 26201da177e4SLinus Torvalds } 26211da177e4SLinus Torvalds 26223cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 26235590ff0dSUlrich Drepper { 26245590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 26255590ff0dSUlrich Drepper } 26265590ff0dSUlrich Drepper 26271da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 26281da177e4SLinus Torvalds { 26291da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 26301da177e4SLinus Torvalds 26311da177e4SLinus Torvalds if (error) 26321da177e4SLinus Torvalds return error; 26331da177e4SLinus Torvalds 2634acfa4380SAl Viro if (!dir->i_op->unlink) 26351da177e4SLinus Torvalds return -EPERM; 26361da177e4SLinus Torvalds 26371b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26381da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26391da177e4SLinus Torvalds error = -EBUSY; 26401da177e4SLinus Torvalds else { 26411da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2642bec1052eSAl Viro if (!error) { 26431da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2644bec1052eSAl Viro if (!error) 2645d83c49f3SAl Viro dont_mount(dentry); 2646bec1052eSAl Viro } 26471da177e4SLinus Torvalds } 26481b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26491da177e4SLinus Torvalds 26501da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 26511da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2652ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 26531da177e4SLinus Torvalds d_delete(dentry); 26541da177e4SLinus Torvalds } 26550eeca283SRobert Love 26561da177e4SLinus Torvalds return error; 26571da177e4SLinus Torvalds } 26581da177e4SLinus Torvalds 26591da177e4SLinus Torvalds /* 26601da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 26611b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 26621da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 26631da177e4SLinus Torvalds * while waiting on the I/O. 26641da177e4SLinus Torvalds */ 26655590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 26661da177e4SLinus Torvalds { 26672ad94ae6SAl Viro int error; 26681da177e4SLinus Torvalds char *name; 26691da177e4SLinus Torvalds struct dentry *dentry; 26701da177e4SLinus Torvalds struct nameidata nd; 26711da177e4SLinus Torvalds struct inode *inode = NULL; 26721da177e4SLinus Torvalds 26732ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26741da177e4SLinus Torvalds if (error) 26752ad94ae6SAl Viro return error; 26762ad94ae6SAl Viro 26771da177e4SLinus Torvalds error = -EISDIR; 26781da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 26791da177e4SLinus Torvalds goto exit1; 26800612d9fbSOGAWA Hirofumi 26810612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26820612d9fbSOGAWA Hirofumi 26834ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 268449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26851da177e4SLinus Torvalds error = PTR_ERR(dentry); 26861da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 26871da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 268850338b88STörök Edwin if (nd.last.name[nd.last.len]) 268950338b88STörök Edwin goto slashes; 26901da177e4SLinus Torvalds inode = dentry->d_inode; 269150338b88STörök Edwin if (!inode) 2692e6bc45d6STheodore Ts'o goto slashes; 26937de9c6eeSAl Viro ihold(inode); 26940622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26950622753bSDave Hansen if (error) 26960622753bSDave Hansen goto exit2; 2697be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2698be6d3e56SKentaro Takeda if (error) 2699be6d3e56SKentaro Takeda goto exit3; 27004ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2701be6d3e56SKentaro Takeda exit3: 27020622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27031da177e4SLinus Torvalds exit2: 27041da177e4SLinus Torvalds dput(dentry); 27051da177e4SLinus Torvalds } 27064ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27071da177e4SLinus Torvalds if (inode) 27081da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27091da177e4SLinus Torvalds exit1: 27101d957f9bSJan Blunck path_put(&nd.path); 27111da177e4SLinus Torvalds putname(name); 27121da177e4SLinus Torvalds return error; 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds slashes: 27151da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27161da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 27171da177e4SLinus Torvalds goto exit2; 27181da177e4SLinus Torvalds } 27191da177e4SLinus Torvalds 27202e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 27215590ff0dSUlrich Drepper { 27225590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 27235590ff0dSUlrich Drepper return -EINVAL; 27245590ff0dSUlrich Drepper 27255590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 27265590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 27275590ff0dSUlrich Drepper 27285590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 27295590ff0dSUlrich Drepper } 27305590ff0dSUlrich Drepper 27313480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 27325590ff0dSUlrich Drepper { 27335590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 27345590ff0dSUlrich Drepper } 27355590ff0dSUlrich Drepper 2736db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 27371da177e4SLinus Torvalds { 2738a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27391da177e4SLinus Torvalds 27401da177e4SLinus Torvalds if (error) 27411da177e4SLinus Torvalds return error; 27421da177e4SLinus Torvalds 2743acfa4380SAl Viro if (!dir->i_op->symlink) 27441da177e4SLinus Torvalds return -EPERM; 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 27471da177e4SLinus Torvalds if (error) 27481da177e4SLinus Torvalds return error; 27491da177e4SLinus Torvalds 27501da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2751a74574aaSStephen Smalley if (!error) 2752f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27531da177e4SLinus Torvalds return error; 27541da177e4SLinus Torvalds } 27551da177e4SLinus Torvalds 27562e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 27572e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 27581da177e4SLinus Torvalds { 27592ad94ae6SAl Viro int error; 27601da177e4SLinus Torvalds char *from; 27611da177e4SLinus Torvalds char *to; 27626902d925SDave Hansen struct dentry *dentry; 27636902d925SDave Hansen struct nameidata nd; 27641da177e4SLinus Torvalds 27651da177e4SLinus Torvalds from = getname(oldname); 27661da177e4SLinus Torvalds if (IS_ERR(from)) 27671da177e4SLinus Torvalds return PTR_ERR(from); 27682ad94ae6SAl Viro 27692ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 27702ad94ae6SAl Viro if (error) 27716902d925SDave Hansen goto out_putname; 27721da177e4SLinus Torvalds 27731da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 27741da177e4SLinus Torvalds error = PTR_ERR(dentry); 27756902d925SDave Hansen if (IS_ERR(dentry)) 27766902d925SDave Hansen goto out_unlock; 27776902d925SDave Hansen 277875c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 277975c3f29dSDave Hansen if (error) 278075c3f29dSDave Hansen goto out_dput; 2781be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2782be6d3e56SKentaro Takeda if (error) 2783be6d3e56SKentaro Takeda goto out_drop_write; 2784db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2785be6d3e56SKentaro Takeda out_drop_write: 278675c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 278775c3f29dSDave Hansen out_dput: 27881da177e4SLinus Torvalds dput(dentry); 27896902d925SDave Hansen out_unlock: 27904ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27911d957f9bSJan Blunck path_put(&nd.path); 27921da177e4SLinus Torvalds putname(to); 27936902d925SDave Hansen out_putname: 27941da177e4SLinus Torvalds putname(from); 27951da177e4SLinus Torvalds return error; 27961da177e4SLinus Torvalds } 27971da177e4SLinus Torvalds 27983480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 27995590ff0dSUlrich Drepper { 28005590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28015590ff0dSUlrich Drepper } 28025590ff0dSUlrich Drepper 28031da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28041da177e4SLinus Torvalds { 28051da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28061da177e4SLinus Torvalds int error; 28071da177e4SLinus Torvalds 28081da177e4SLinus Torvalds if (!inode) 28091da177e4SLinus Torvalds return -ENOENT; 28101da177e4SLinus Torvalds 2811a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28121da177e4SLinus Torvalds if (error) 28131da177e4SLinus Torvalds return error; 28141da177e4SLinus Torvalds 28151da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28161da177e4SLinus Torvalds return -EXDEV; 28171da177e4SLinus Torvalds 28181da177e4SLinus Torvalds /* 28191da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 28201da177e4SLinus Torvalds */ 28211da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 28221da177e4SLinus Torvalds return -EPERM; 2823acfa4380SAl Viro if (!dir->i_op->link) 28241da177e4SLinus Torvalds return -EPERM; 28257e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 28261da177e4SLinus Torvalds return -EPERM; 28271da177e4SLinus Torvalds 28281da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 28291da177e4SLinus Torvalds if (error) 28301da177e4SLinus Torvalds return error; 28311da177e4SLinus Torvalds 28327e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2833aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2834aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2835aae8a97dSAneesh Kumar K.V error = -ENOENT; 2836aae8a97dSAneesh Kumar K.V else 28371da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 28387e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2839e31e14ecSStephen Smalley if (!error) 28407e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 28411da177e4SLinus Torvalds return error; 28421da177e4SLinus Torvalds } 28431da177e4SLinus Torvalds 28441da177e4SLinus Torvalds /* 28451da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 28461da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 28471da177e4SLinus Torvalds * newname. --KAB 28481da177e4SLinus Torvalds * 28491da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 28501da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 28511da177e4SLinus Torvalds * and other special files. --ADM 28521da177e4SLinus Torvalds */ 28532e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 28542e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 28551da177e4SLinus Torvalds { 28561da177e4SLinus Torvalds struct dentry *new_dentry; 28572d8f3038SAl Viro struct nameidata nd; 28582d8f3038SAl Viro struct path old_path; 285911a7b371SAneesh Kumar K.V int how = 0; 28601da177e4SLinus Torvalds int error; 28611da177e4SLinus Torvalds char *to; 28621da177e4SLinus Torvalds 286311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2864c04030e1SUlrich Drepper return -EINVAL; 286511a7b371SAneesh Kumar K.V /* 286611a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 286711a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 286811a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 286911a7b371SAneesh Kumar K.V */ 287011a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 287111a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 287211a7b371SAneesh Kumar K.V return -ENOENT; 287311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 287411a7b371SAneesh Kumar K.V } 2875c04030e1SUlrich Drepper 287611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 287711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 287811a7b371SAneesh Kumar K.V 287911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 28801da177e4SLinus Torvalds if (error) 28812ad94ae6SAl Viro return error; 28822ad94ae6SAl Viro 28832ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28841da177e4SLinus Torvalds if (error) 28851da177e4SLinus Torvalds goto out; 28861da177e4SLinus Torvalds error = -EXDEV; 28872d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 28881da177e4SLinus Torvalds goto out_release; 28891da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 28901da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 28916902d925SDave Hansen if (IS_ERR(new_dentry)) 28926902d925SDave Hansen goto out_unlock; 289375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 289475c3f29dSDave Hansen if (error) 289575c3f29dSDave Hansen goto out_dput; 2896be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2897be6d3e56SKentaro Takeda if (error) 2898be6d3e56SKentaro Takeda goto out_drop_write; 28992d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2900be6d3e56SKentaro Takeda out_drop_write: 290175c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 290275c3f29dSDave Hansen out_dput: 29031da177e4SLinus Torvalds dput(new_dentry); 29046902d925SDave Hansen out_unlock: 29054ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29061da177e4SLinus Torvalds out_release: 29071d957f9bSJan Blunck path_put(&nd.path); 29082ad94ae6SAl Viro putname(to); 29091da177e4SLinus Torvalds out: 29102d8f3038SAl Viro path_put(&old_path); 29111da177e4SLinus Torvalds 29121da177e4SLinus Torvalds return error; 29131da177e4SLinus Torvalds } 29141da177e4SLinus Torvalds 29153480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29165590ff0dSUlrich Drepper { 2917c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29185590ff0dSUlrich Drepper } 29195590ff0dSUlrich Drepper 29201da177e4SLinus Torvalds /* 29211da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29221da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29231da177e4SLinus Torvalds * Problems: 29241da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29251da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29261da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2927a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29281da177e4SLinus Torvalds * story. 29291da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29301b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29311da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29321da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2933a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 29341da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 29351da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 29361da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2937a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 29381da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 29391da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 29401da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 2941e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 29421b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 29431da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 2944c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 29451da177e4SLinus Torvalds * locking]. 29461da177e4SLinus Torvalds */ 294775c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 29481da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 29491da177e4SLinus Torvalds { 29501da177e4SLinus Torvalds int error = 0; 29519055cba7SSage Weil struct inode *target = new_dentry->d_inode; 29521da177e4SLinus Torvalds 29531da177e4SLinus Torvalds /* 29541da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 29551da177e4SLinus Torvalds * we'll need to flip '..'. 29561da177e4SLinus Torvalds */ 29571da177e4SLinus Torvalds if (new_dir != old_dir) { 2958f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 29591da177e4SLinus Torvalds if (error) 29601da177e4SLinus Torvalds return error; 29611da177e4SLinus Torvalds } 29621da177e4SLinus Torvalds 29631da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 29641da177e4SLinus Torvalds if (error) 29651da177e4SLinus Torvalds return error; 29661da177e4SLinus Torvalds 2967d83c49f3SAl Viro if (target) 29681b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 29699055cba7SSage Weil 29701da177e4SLinus Torvalds error = -EBUSY; 29719055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 29729055cba7SSage Weil goto out; 29739055cba7SSage Weil 29743cebde24SSage Weil if (target) 29753cebde24SSage Weil shrink_dcache_parent(new_dentry); 29761da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 29779055cba7SSage Weil if (error) 29789055cba7SSage Weil goto out; 29799055cba7SSage Weil 29801da177e4SLinus Torvalds if (target) { 29811da177e4SLinus Torvalds target->i_flags |= S_DEAD; 2982d83c49f3SAl Viro dont_mount(new_dentry); 2983d83c49f3SAl Viro } 29849055cba7SSage Weil out: 29859055cba7SSage Weil if (target) 29861b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 2987e31e14ecSStephen Smalley if (!error) 2988349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 29891da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 29901da177e4SLinus Torvalds return error; 29911da177e4SLinus Torvalds } 29921da177e4SLinus Torvalds 299375c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 29941da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 29951da177e4SLinus Torvalds { 299651892bbbSSage Weil struct inode *target = new_dentry->d_inode; 29971da177e4SLinus Torvalds int error; 29981da177e4SLinus Torvalds 29991da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30001da177e4SLinus Torvalds if (error) 30011da177e4SLinus Torvalds return error; 30021da177e4SLinus Torvalds 30031da177e4SLinus Torvalds dget(new_dentry); 30041da177e4SLinus Torvalds if (target) 30051b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 300651892bbbSSage Weil 30071da177e4SLinus Torvalds error = -EBUSY; 300851892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 300951892bbbSSage Weil goto out; 301051892bbbSSage Weil 30111da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 301251892bbbSSage Weil if (error) 301351892bbbSSage Weil goto out; 301451892bbbSSage Weil 3015bec1052eSAl Viro if (target) 3016d83c49f3SAl Viro dont_mount(new_dentry); 3017349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30181da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 301951892bbbSSage Weil out: 30201da177e4SLinus Torvalds if (target) 30211b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30221da177e4SLinus Torvalds dput(new_dentry); 30231da177e4SLinus Torvalds return error; 30241da177e4SLinus Torvalds } 30251da177e4SLinus Torvalds 30261da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30271da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30281da177e4SLinus Torvalds { 30291da177e4SLinus Torvalds int error; 30301da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 303159b0df21SEric Paris const unsigned char *old_name; 30321da177e4SLinus Torvalds 30331da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 30341da177e4SLinus Torvalds return 0; 30351da177e4SLinus Torvalds 30361da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 30371da177e4SLinus Torvalds if (error) 30381da177e4SLinus Torvalds return error; 30391da177e4SLinus Torvalds 30401da177e4SLinus Torvalds if (!new_dentry->d_inode) 3041a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 30421da177e4SLinus Torvalds else 30431da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 30441da177e4SLinus Torvalds if (error) 30451da177e4SLinus Torvalds return error; 30461da177e4SLinus Torvalds 3047acfa4380SAl Viro if (!old_dir->i_op->rename) 30481da177e4SLinus Torvalds return -EPERM; 30491da177e4SLinus Torvalds 30500eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 30510eeca283SRobert Love 30521da177e4SLinus Torvalds if (is_dir) 30531da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 30541da177e4SLinus Torvalds else 30551da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3056123df294SAl Viro if (!error) 3057123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 30585a190ae6SAl Viro new_dentry->d_inode, old_dentry); 30590eeca283SRobert Love fsnotify_oldname_free(old_name); 30600eeca283SRobert Love 30611da177e4SLinus Torvalds return error; 30621da177e4SLinus Torvalds } 30631da177e4SLinus Torvalds 30642e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 30652e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 30661da177e4SLinus Torvalds { 30671da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 30681da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 30691da177e4SLinus Torvalds struct dentry *trap; 30701da177e4SLinus Torvalds struct nameidata oldnd, newnd; 30712ad94ae6SAl Viro char *from; 30722ad94ae6SAl Viro char *to; 30732ad94ae6SAl Viro int error; 30741da177e4SLinus Torvalds 30752ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 30761da177e4SLinus Torvalds if (error) 30771da177e4SLinus Torvalds goto exit; 30781da177e4SLinus Torvalds 30792ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 30801da177e4SLinus Torvalds if (error) 30811da177e4SLinus Torvalds goto exit1; 30821da177e4SLinus Torvalds 30831da177e4SLinus Torvalds error = -EXDEV; 30844ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 30851da177e4SLinus Torvalds goto exit2; 30861da177e4SLinus Torvalds 30874ac91378SJan Blunck old_dir = oldnd.path.dentry; 30881da177e4SLinus Torvalds error = -EBUSY; 30891da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 30901da177e4SLinus Torvalds goto exit2; 30911da177e4SLinus Torvalds 30924ac91378SJan Blunck new_dir = newnd.path.dentry; 30931da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 30941da177e4SLinus Torvalds goto exit2; 30951da177e4SLinus Torvalds 30960612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 30970612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 30984e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 30990612d9fbSOGAWA Hirofumi 31001da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31011da177e4SLinus Torvalds 310249705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31031da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31041da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31051da177e4SLinus Torvalds goto exit3; 31061da177e4SLinus Torvalds /* source must exist */ 31071da177e4SLinus Torvalds error = -ENOENT; 31081da177e4SLinus Torvalds if (!old_dentry->d_inode) 31091da177e4SLinus Torvalds goto exit4; 31101da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31111da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31121da177e4SLinus Torvalds error = -ENOTDIR; 31131da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31141da177e4SLinus Torvalds goto exit4; 31151da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31161da177e4SLinus Torvalds goto exit4; 31171da177e4SLinus Torvalds } 31181da177e4SLinus Torvalds /* source should not be ancestor of target */ 31191da177e4SLinus Torvalds error = -EINVAL; 31201da177e4SLinus Torvalds if (old_dentry == trap) 31211da177e4SLinus Torvalds goto exit4; 312249705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31231da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31241da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31251da177e4SLinus Torvalds goto exit4; 31261da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31271da177e4SLinus Torvalds error = -ENOTEMPTY; 31281da177e4SLinus Torvalds if (new_dentry == trap) 31291da177e4SLinus Torvalds goto exit5; 31301da177e4SLinus Torvalds 31319079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 31329079b1ebSDave Hansen if (error) 31339079b1ebSDave Hansen goto exit5; 3134be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3135be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3136be6d3e56SKentaro Takeda if (error) 3137be6d3e56SKentaro Takeda goto exit6; 31381da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 31391da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3140be6d3e56SKentaro Takeda exit6: 31419079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 31421da177e4SLinus Torvalds exit5: 31431da177e4SLinus Torvalds dput(new_dentry); 31441da177e4SLinus Torvalds exit4: 31451da177e4SLinus Torvalds dput(old_dentry); 31461da177e4SLinus Torvalds exit3: 31471da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 31481da177e4SLinus Torvalds exit2: 31491d957f9bSJan Blunck path_put(&newnd.path); 31502ad94ae6SAl Viro putname(to); 31511da177e4SLinus Torvalds exit1: 31521d957f9bSJan Blunck path_put(&oldnd.path); 31531da177e4SLinus Torvalds putname(from); 31542ad94ae6SAl Viro exit: 31551da177e4SLinus Torvalds return error; 31561da177e4SLinus Torvalds } 31571da177e4SLinus Torvalds 3158a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 31595590ff0dSUlrich Drepper { 31605590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 31615590ff0dSUlrich Drepper } 31625590ff0dSUlrich Drepper 31631da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 31641da177e4SLinus Torvalds { 31651da177e4SLinus Torvalds int len; 31661da177e4SLinus Torvalds 31671da177e4SLinus Torvalds len = PTR_ERR(link); 31681da177e4SLinus Torvalds if (IS_ERR(link)) 31691da177e4SLinus Torvalds goto out; 31701da177e4SLinus Torvalds 31711da177e4SLinus Torvalds len = strlen(link); 31721da177e4SLinus Torvalds if (len > (unsigned) buflen) 31731da177e4SLinus Torvalds len = buflen; 31741da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 31751da177e4SLinus Torvalds len = -EFAULT; 31761da177e4SLinus Torvalds out: 31771da177e4SLinus Torvalds return len; 31781da177e4SLinus Torvalds } 31791da177e4SLinus Torvalds 31801da177e4SLinus Torvalds /* 31811da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 31821da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 31831da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 31841da177e4SLinus Torvalds */ 31851da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 31861da177e4SLinus Torvalds { 31871da177e4SLinus Torvalds struct nameidata nd; 3188cc314eefSLinus Torvalds void *cookie; 3189694a1764SMarcin Slusarz int res; 3190cc314eefSLinus Torvalds 31911da177e4SLinus Torvalds nd.depth = 0; 3192cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3193694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3194694a1764SMarcin Slusarz return PTR_ERR(cookie); 3195694a1764SMarcin Slusarz 3196694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 31971da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3198cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3199694a1764SMarcin Slusarz return res; 32001da177e4SLinus Torvalds } 32011da177e4SLinus Torvalds 32021da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32031da177e4SLinus Torvalds { 32041da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32051da177e4SLinus Torvalds } 32061da177e4SLinus Torvalds 32071da177e4SLinus Torvalds /* get the link contents into pagecache */ 32081da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32091da177e4SLinus Torvalds { 3210ebd09abbSDuane Griffin char *kaddr; 32111da177e4SLinus Torvalds struct page *page; 32121da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3213090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32141da177e4SLinus Torvalds if (IS_ERR(page)) 32156fe6900eSNick Piggin return (char*)page; 32161da177e4SLinus Torvalds *ppage = page; 3217ebd09abbSDuane Griffin kaddr = kmap(page); 3218ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3219ebd09abbSDuane Griffin return kaddr; 32201da177e4SLinus Torvalds } 32211da177e4SLinus Torvalds 32221da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32231da177e4SLinus Torvalds { 32241da177e4SLinus Torvalds struct page *page = NULL; 32251da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32261da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32271da177e4SLinus Torvalds if (page) { 32281da177e4SLinus Torvalds kunmap(page); 32291da177e4SLinus Torvalds page_cache_release(page); 32301da177e4SLinus Torvalds } 32311da177e4SLinus Torvalds return res; 32321da177e4SLinus Torvalds } 32331da177e4SLinus Torvalds 3234cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 32351da177e4SLinus Torvalds { 3236cc314eefSLinus Torvalds struct page *page = NULL; 32371da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3238cc314eefSLinus Torvalds return page; 32391da177e4SLinus Torvalds } 32401da177e4SLinus Torvalds 3241cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 32421da177e4SLinus Torvalds { 3243cc314eefSLinus Torvalds struct page *page = cookie; 3244cc314eefSLinus Torvalds 3245cc314eefSLinus Torvalds if (page) { 32461da177e4SLinus Torvalds kunmap(page); 32471da177e4SLinus Torvalds page_cache_release(page); 32481da177e4SLinus Torvalds } 32491da177e4SLinus Torvalds } 32501da177e4SLinus Torvalds 325154566b2cSNick Piggin /* 325254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 325354566b2cSNick Piggin */ 325454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 32551da177e4SLinus Torvalds { 32561da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 32570adb25d2SKirill Korotaev struct page *page; 3258afddba49SNick Piggin void *fsdata; 3259beb497abSDmitriy Monakhov int err; 32601da177e4SLinus Torvalds char *kaddr; 326154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 326254566b2cSNick Piggin if (nofs) 326354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 32641da177e4SLinus Torvalds 32657e53cac4SNeilBrown retry: 3266afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 326754566b2cSNick Piggin flags, &page, &fsdata); 32681da177e4SLinus Torvalds if (err) 3269afddba49SNick Piggin goto fail; 3270afddba49SNick Piggin 32711da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 32721da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 32731da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3274afddba49SNick Piggin 3275afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3276afddba49SNick Piggin page, fsdata); 32771da177e4SLinus Torvalds if (err < 0) 32781da177e4SLinus Torvalds goto fail; 3279afddba49SNick Piggin if (err < len-1) 3280afddba49SNick Piggin goto retry; 3281afddba49SNick Piggin 32821da177e4SLinus Torvalds mark_inode_dirty(inode); 32831da177e4SLinus Torvalds return 0; 32841da177e4SLinus Torvalds fail: 32851da177e4SLinus Torvalds return err; 32861da177e4SLinus Torvalds } 32871da177e4SLinus Torvalds 32880adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 32890adb25d2SKirill Korotaev { 32900adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 329154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 32920adb25d2SKirill Korotaev } 32930adb25d2SKirill Korotaev 329492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 32951da177e4SLinus Torvalds .readlink = generic_readlink, 32961da177e4SLinus Torvalds .follow_link = page_follow_link_light, 32971da177e4SLinus Torvalds .put_link = page_put_link, 32981da177e4SLinus Torvalds }; 32991da177e4SLinus Torvalds 33002d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3301cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33021da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33031da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33041da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33051da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33061da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33071da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33081da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33091da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33101da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33110adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33121da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33131da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3314c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3315d1811465SAl Viro EXPORT_SYMBOL(kern_path); 331616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3317f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33181da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33201da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33211da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33221da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33231da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33241da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33291da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33301da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 33311da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3332